Anyone running a site that has user-to-user interactions has to provide risk-assessments for each of:
* CSAM;
* Grooming;
* Terrorism;
* Under-age access to porn;
* Modern slavery;
... and more.
For each of the above there must be written policies about how the limitations are enforced, and the procedures taken for each of the risks identified.
I've download some, but not all, of the explanatory and guidance documentation and it amounts to around 1100 pages of legalese so far.