Google "Sakeru Gummy vs. Long Sakeru Gummy" if you don't get the reference in the title, your life will be enriched.

The Lora helps add length but not necessarily girth to your futa gens. It mostly works but don't expect good control over thickness. huge_penis seems to help a lot as well as prompting for situations where you would see a good bit of dong.(AI seems to try to get the whole penis in frame.)

"Horse_penis" in the negative prompt might also be helpful.

Example Prompt: futanari, abslonpen, looking_at_viewer, solo, huge_penis, testicles,small_breasts, mature_female, feet,

FYI as per usual this dataset contains zero men so if it works for men, great but I'm not testing for it.