Welcome to the SDXL version. For SD1.5 version, click here.
Note: Re-Published because I wrongly tagged the old one as SD 1.5...
With this LoRA I tried to focus on the features of a well-trained female belly. I used a set of 58 photos. It should work with standing and lying poses as well as realistic and non-realistic models.
It works best with a strength from 0.6 - 0.8. While it doesn't require a trigger, you may use following keywords to further specify the results: navel, belly button, linea alba, lateral abdominal lines, hip bones, Apollo's belt (make sure to add "belt" to negative prompts) or V-cut, pubic mound. You may also try "vertical belly button" or "round belly button", but that might not work reliably. See below picture for reference.
Don't forget to share your images, I'd love to see what you have created. And if you have a few minutes left, make sure to have a look at my other LoRAs. Happy prompting!