I did not make this. I found it here: https://huggingface.co/Fake-Person/Frequent_futa/tree/main
It is a merge of another futa model with Elysium.

It does exactly as it says on the tin. Produces futanari in an anime-like style. Does it somewhat consistently too, in a few certain compositions.
It can also do normal women just fine, but that isn't what you're here for, is it?

Standard settings work fine. All example images are unedited and use the standard settings.

For the negative, I usually go with:

lowres, low res, text, error, cropped, worst quality, low quality, normal quality, jpeg artifacts, artist signature, watermark, text, username, blurry, out of focus, censored, out of frame, b&w, mask, selfie, 3d, sketch, cartoon, extra arms,

For a starting prompt, I'd recommend this:

futanari, penis, masterpiece, high quality, 1girl, solo

Then start generating and see what works for you.