Just echoing what remiquise said. I'm super anti-artistic censorship. For me the only responsibility an adult author has is to mark their work as 18+, as much as people want the fiction they consume to be neatly organized filtered, it is ultimately their own responsibility to control what they read.
I personally put of content warnings, as well as unnecessary personal info, because I don't have the energy to deal with backlash from people getting upset about the subjects in my comic, or tell me I'm doing 'Z' wrong. I've also considered putting up a "this is just a work of fiction" statement in case the wrong people find my work and try to sue, apparently there is a real place sharing the same name as an establishment in my story. Whoopee, fun! You also have May Leitz, a horror fan and writer of transgressive horror who uses warnings because she herself has been triggered when being thrusts into disturbing media without warning, but as far as I know her experience is more with videos than books.
On the other hand, though, there are folks like Gretchen Felker-Martin, a transgressive horror writer who never puts up any warnings because for her it is up to the reader to put the book down if it's too much. (Which, yes, the reader should do that if they can't handle the subjects in a piece of fiction.) Gretchen is also known for the type of dark fiction she makes, so it shouldn't be a surprise if a passage in her novel is kinda messed up, you should just put it down or take it in doses if you don't have an iron stomach.
So again, my whole stance is it's not the author's responsibility to babysit their readers, especially if they're adults. Except putting up an age rating for legal reasons. If someone is influenced to do bad stuff because of fiction, or dangerously misses the mark due to their own media illiteracy, or gets extremely parasocial about it, that person shouldn't be consuming fiction to begin with. I would say something about fear mongering or hate speech, but if you have those in your fiction you weren't a moral person to begin with, and it should still be up the the reader how they deal with something like that.