On any browse page, like https://itch.io/games/genre-visual-novel you can append /sfw to apply a “not-NSFW” filter to the results –> https://itch.io/games/genre-visual-novel/sfw
Likewise, you can append /nsfw to do the opposite
The reason why publishing an NSFW project causes the NSFW games to show up on your account by default is because many people who publish NSFW games would attempt to search for their own game, not see it, then message support thinking something is wrong with their account or our system. This was the easiest way to reduce the load on our team and clear up any confusion about how projects are indexed.
Hope that makes sense.