Here’s the younger version of the kids™ in the show’s style
I’ll just copy paste their description from the first artwork down below:

Zap Apple

Rainbow and Applejack's first-born child and Lil' Cheese's best mate. Zap is a daydreamer and has a gentle soul, he's that one ripped nerd that likes writing and drawing things just for the sake of it. Exploring and discovering new things and places is what really makes his eyes glow (history and geography hoe), so he can be usually seen carrying his saddlebag around all the time (you never know when you're gonna need sketching and exploring supplies). Zap also loves puzzles and is a huge fanboy of Daring Do Books like Dash (and adventure books in general. AJ swears it's because Rainbow used to read so many Daring Doo adventures to her belly when she was pregnant). While he can be smart, he tends to over-thinks things, Zap has a wide imagination and is easily one of the most compassionate ponies around, though he used to be easily coaxed into fights or manipulated by his feelings. Like a good apple family member, the boy loves farm life and has a strong fraternal instinct, but his nature just doesn't allow him to settle there, though he still finds some peace whenever he's back in the environment he grew up in.

Random facts:

- Zap loved wearing his Ma's hat so much that she gave one for him as a gift in a Hearts Warming;

- He lost part of his his right ear to a bad fall when he and some friends went exploring one of his first off-limits area;

- Loves collecting comic books and stamps;

- AJ entered labor right during a Zap Apple harvest (Yep, that's exactly how he got his name);

- Inherited AJ's stare and lie detector;

- Upon noticing Zap's resemblance to his great grandmother, Rainbow nicknamed him Baby Smith.

Applejoy

Rainbow and Applejack's middle child. Applejoy doesn't take her name for granted, she's a total sunshine and bringing people happiness is what really makes her happy. She tends to be famous for getting a bunch of bruises all the time and being a little too reckless, so much so she lost two of her teeth out of pure clumsiness when she was little and had to wait until they began to grow to get them back (still has the best smile), and she also used to break her flying goggles at least once a week. The girl is also very outspoken and sincere, though it can end up being a problem sometimes. Applejoy is the family's Poly Athlete and has strong and fast wings (as well as legs, the girl is speed itself), she doesn't do very well in school but makes for it in sports and is very disciplined when it comes to it (Rainbow is her personal coach for every occasion). She hates losing, but tries her best to be a good sport and not to show she's upset most of the time. It was also awfully difficult for Applejack to handle her being all over the place when she learned how to use her wings (no need to say she was very grateful when her next child was born an earth pony).

Random facts: — Inherited Rainbow's habit of napping on trees (Applejack didn't like the idea, she was always concerned her children were gonna fall and hurt themselves for being too cloud-headed);

- Loves to indulge in her mother's sugary treats;- Rainbow started calling her junior (or AJJ) because her name abbreviation is the same as her ma's. No need to say the nickname was a success;

- Sleepwalker;

- The bandana she uses around her neck is a part of the fabric of an old sheet she used to nap with;

- Likes a bunch of crafts, specially wood-carving, but isn't really gifted at most of them (doesn't matter because she always tries her best every time).

Cider Splash

Rainbow and Applejack's youngest child and Tank's best buddy. Cider Splash a performer at heart, he's a innate dancer and plays multiple instruments very decently, he's the loudest of the bunch in every way and talks everyone's ears off (some conversations can also turn into musical numbers for no apparent reason). He's the most headstrong and stubborn out of the three, so he'll almost always get really deep into a project (or anything, really) when he sets his mind in it. He has blessed hoofs like AJ and is by far the one who ends up helping with the applebucking stuff the most, though he has a natural charm with the farm animals and prefers playing with them (his love for animal plushies wasn't taken for granted). He also indulges in cooking (mostly by Big Sugar's influence). Cider was always jealous of his sibling's ability to fly, so RD tries to compensate by taking him for a ride every once in a while and making sure he's the first one to get Wonderbolts tickets whenever they perform.

Random facts: — His love for music started when Applejack bought him a toy guitar to get him out of his tantrums when he was little. Later, his grandpa Bow Hothoof gave him a mini drum set as a birthday gift. AJ and RD weren't very happy when he started playing it all the time and making a bunch of noise, but they eventually saw potential in it and started investing in his inate talent;

- No need to say cider is his favorite drink ever;

- His bandana was a handmade gift from his Aunt Applebloom.

Florence

Fluttershy's big baby and Agate's older step-sister. Florence is a very resourceful and hard-working young mare, though she tends to spends way too much energy worrying about results and is almost constantly on the verge of outright panic (she's usually seen gritting her teeth or generally flipping out, no need to say she does not fare well under stress, specially when she is given a task to complete). Florence is known to be very sensible and intelligent, and even though she sometimes puts her own paranoia before common sense, she usually manages to find logical solutions to problems. She learned how to deal with stress by canalizing it into something productive, thanks to Rarimom (which ended up being another source of anxiety, ironically). She also has very strong beliefs, and when forced to question them, she becomes very upset. Despite that, Florence is extremely loyal and kind and will go out of her way to help other ponies.

Random facts: — Her scarf was given by Rarity, it made her feel safe when she was little, and she still uses it until this day (Her moms had to bribe with her in order to get her to let them clean and wash it after months of using it non-stop);

- Probably has OCD;

- She has also been known to retreat into her imagination when under extreme stress, often picturing peaceful, grassy fields or tranquil landscapes to calm herself down.

- Florence loves her coffee, tea and Fluttermum's pets more than her life (She loved growing up around pets, they still give her a sense of calm and relaxation. Her mom used to use them to calm her down when she was crying or couldn't sleep, she would almost always fall asleep after caressing some pet's ear for a while)

Agate

Rarity’s most precious gem and Florence’s little step-sister. Agate has been a very independent gal since she was little, she has been described as curious, monotone and sarcastic, and also appears to be more logical and mature than some of her peers, typically being the one to call them out on their ignorance, she’s inclined to remain passive and stoical to most things that happen around her. She has a fuckton control over her emotions and wears a neutral expression about 80% of the time, but is actually a pretty chill gal and has a very good (and weird) sense of humor. Agate has a great eye for photography (specially Avant-garde stuff) and turns out working as a professional photographer in the future.

Random facts: — Lowkey a huge mystery fan and computer nerd;

- Has a huge soft spot for Fluttermom's pets since she first came in contact with one, she can’t help but to smile the whole time she’s around them;

- Discord's favorite gal right next to Fluttershy.

Lil' Cheese

So let's get this out of the way, the script says Lil' Cheese is a colt, but many people see them as a filly, so they ended up being non-binary in my headcanon because I couldn't decide their gender (but go with whatever suits you better).

"Don't worry, Zap and Cheese got another infallible plan". Cheesecake, AKA "Lil' Cheese", is first and foremost known for the ability to talk their ass off anytime of the day for whatever reason (they used to spend most of their time besides their mom, so no need to mention that they practically picked up all her goofiness and energy by osmosis), they're also an excellent actor and are known as "The God of Puns". They’re generally a popular and gifted student, however, they're foul-mouthed and kind of competitive (but despite that, they are generally well liked and always looking after their friends). Lil' Cheese uses their innate talent for comedy and natural charm and charisma to help attract attention to their mum's bakery. Cheese had pretty deep random conversations with Pinkie since very little, so they turned out to be a pretty good conversationalist and improviser.

Big Sugar/Little Mac

I don't really have a very elaborate description for him (sorry peeps), but I imagine Sugar as a very sweet (pun intended) Big Baker Boy that loves cooking (and eating, most of all). He has that big bro energy and always gives the best hugs, but can also have with no mercy when messing around with his peers. He's very well liked around Ponyville and known for his extroverted and warm nature, though he may care way to much about other's opinions and tends to take a lot of them personally. Being a proud member of the Apple Family, he's the embodiment hard-work and loves working on the farm, but his heart always feel in the right place whenever he's preparing meals for other ponies.