I actually documented how I generated this picture over here:
https://www.fimfiction.net/group/216589/ai-art-group/thread/515984/creating-ai-art-from-a-bad-drawing

For anyone not wanting to go over there, I drew a bad line drawing of a pony (I could have done better, but I was deliberately not putting too much effort into it, since I intended the ai to do most of the lifting.), then I ran it through img2img with this prompt:
`Prompt: A cute happy pony standing on a hill with one leg in the air, one ear down, line art
Negative prompt: EasyNegative boring_e621`

Then I edited the line drawing it generated, and did inpainting on the edit. Then I went to txt2img with a revised prompt (Listed on the linked thread. I did specify fur and eye colors, for example.), put the line are in controlnet using the lineart model, generated a new image with that, and threw that through img2img.

I was largely experimenting to see how well that worked… and I think it works pretty well!