Strength at 1 seems to work best. No trigger words required, though vulva or labia in the prompt certainly help. Because Flux doesn't have training on nude anatomy, this version is merged with 80% of MysticXXX lora to properly size and place the trained vulva data. It doesn't require mysticXXX, but I do appreciate his work and can be found here:

https://civitai.com/models/1295758/nsfw-flux-mystic-xxx