Illegal or fraudulent content: Onlyfans does not allow you to post anything that is considered illegal in any way. Nor can you post fraudulent material that constitutes posting other people's content and citing it as your own. The “yes” is based on the username that the content creator sees. Technically, you could use your name as your username (which can make you less anonymous).
The creators we talk to publish pornographic content, and this makes up the vast majority of the content on the platform. You have to consider that, if that's what you want to do, it's sex work and it comes with a lot of the same problems that you would encounter throughout the adult industry.