I LOVE Unreal Engine 5. I'm no expert but I like playing around with it. And if you know your VFX, lots of movie and TV productions are made with Unreal Engine now.
I suspect that it would not lend anything to porn. To have a setup like
The Volume I think its called would be expensive for any porn shoot, and just be a waste of money because it would just be distracting, and probably look stupid anyway.