AO3 is actually the perfect example of how not having censorship of any kind actually makes it *much easier* to avoid triggering or disturbing content that you don't want to see.
I almost never stumble into a fic with content that I'm not at all comfortable with, because the lack of censorship means that everybody tags their shit appropriately. It's super easy to read the ingredients on the tin of each fic and decide if it's for me or not. Meanwhile, on other social media websites where posts are getting incorrectly flagged for being NSFW and people are doing shit like censoring the words "death" or "kill," I end up seeing inappropriate or disturbing content all the fucking time, because it's *never* labelled, because people are afraid to label their shit with tags that might get it removed, so there's no way to filter any of it out!
If you are actually someone who really doesn't ever want to see NSFW content then that is completely possible on ao3 because M rated content is allowed on there, so it's all clearly labelled as such. if you have any "disturbing" topics or potential triggers you never ever want to see, it's easy to filter them out because ao3 allows things to be labelled with stuff like "pedophilia" or "dub-con" so everything is CLEARLY LABELLED! Of course there are going to be people who don't tag everything correctly but I've been on there for over a decade and I've hardly ever seen it happen. People take tagging etiquette very seriously, because it benefits everyone.
Remember how in Prohibition they banned all alcohol of any kind and so alcohol still existed in America but the production went underground and since none of the distilleries were being regulated, a lot of people ended up getting sick because there was all sorts of who knows what kind of toxic shit in their drinks? And then when America re-legalized alcohol, they were able to once again regulate the production of it and literally all alcoholic drinks became safer as a result? And instead of being sold moonshine in an unlabeled mason jar, now all alcoholic drinks have to have very specific information listed on them like alcohol content, ingredients, and allergen risks, so that people know exactly what they're putting in their bodies? Yeah this is a bit like that.