Normally I err on the side of ‘art’ being separated from actual pictures/recordings of abuse. It falls under the “I don’t like what you have to say, but I will defend your right to say it” idea.
Photorealistic images of CP? I think that crosses the line, and needs to be treated as if it was actual CP as it essentially enables real CP to proliferate.
The issue here is that it enables those who would make the actual CP to hide their work easier in the flood of generated content.
Animesque art is one thing, photorealistic is another. Neither actually harms an underaged person by existing, but photorealistic enables actual abusers to hide themselves easily. So IMO, photorealistic ‘art’ of this sort needs to be criminalized so that it can not be used as a mask for actual CP.