There are a lot of great figure studies in art-book form that are folks posing naked in a neutral (non-sexual) way. That can give you a sense for how to portray them in that fashion.
I like the "Art Models" series: https://www.amazon.com/Art-Models-Drawing-Painting-Sculpting-ebook/dp/B004ZN80FU/
You can also look up guides on sexual-coded body language to make sure you aren't unwittingly drawing a naked figure exhibiting that kind of body language (unless you explicitly want to).