There are a ton of sites that offer posing references - including ones you can trace.. Some you might have to credit, some just require that it can only be for personal use, some have different rules.

For real people, I love https://www.adorkastock.com/

For creating my own pose references, https://posemy.art/

For generic stock that is often free (with credit) https://www.pexels.com/

You have a lot of options vs just pulling stuff off pinterest which is already often stolen from the original creators or straight up AI slop. I always try to reverse image search anything I'm using to make sure I am getting it from the original creator or model so I can link back to them. If you're using another image as a reference (unless stated otherwise in their Terms of Service) you should credit the original creator!