How many legs is enough? You decide! This LoRA can produce centipede girls but also can enhance insect girls. I tried to keep some flexibility, so you may need to do some cherry picking to get what you're looking for.
A weight of 1-1.3 for the LoRA and initial generation works well, and 1-1.3 for the trigger word "c3nt1p3d3" - then try lowering the LoRA to 0.7 for upscaling. Adjusting the LoRA seems to make it more bug-like, and the trigger word more centipede-like.
Add "centipede" and/or "long tail" to make them more centipede-ish, "bug girl" or "insect woman" for added insecty-ness. Also "insect arms", "insect legs", and "many legs" seem to have varying effects.