Not to keep beating the dead horse, but I’m not sure newer creators know the difference between a boundary and a preference
A preference is something like, “I don’t want my character to be drawn in ship art.”
A boundary is something like, “If you draw ship art of my character and I see it, I’ll block you.”
They are not interchangeable. You can prefer something and have boundaries regarding that something, as seen in the above example, but they are not one in the same.
A preference is what you would like to happen/not happen. You can always suggest preferences, but they are just that: preferences. What you like won’t always happen, but you can always say that you’d want it to.
A boundary is, in this context, a sort of reaction towards something you’re uncomfortable with. It’s a safety feature in any kind of relationship, including one between creators and fans. This can include blocking certain terms from appearing on your page- this is where the interplay between preference and boundary can come in, because you can say that you want anyone making art of your character that is against your preferences to use a specific tag that you can block.
It’s very important to remember that no one has to follow your preferences. It’s also important to remember that boundaries are largely a personal thing and not something multiple parties have to agree to; I’d personally compare it to wearing a seatbelt when in a car with someone else, it’s something that’ll keep you safe if something happens, but the driver doesn’t necessarily have to agree with you doing so. A boundary is self-preservation. You can’t control what other people do, but you can control what your response is to what other people do.
A lot of creators today don’t seem to really get this difference, though. They conflate the two probably without realizing it (thank you 2020-era mcyt fans /neg), and so it falls to other fans to protect the creator’s peace instead of the creator protecting their own; people are always going to do whatever the hell they want to do, especially when it comes to creative expression like fanart and fanfiction.
While it is probably a little rude to go against a creator’s preferences with art, there’s usually nothing actually mortally objectionable about it. You aren’t a bad person if you draw Character X with wings when the creator doesn’t want that done, they don’t get to determine what you can and can’t create.
What creators can do is set boundaries with their fans. Make a tag specifically for things they don’t want to see that they can block (this has been a practice for YEARS on social media, tumblr included.) They can state that anyone making art they’re uncomfortable with will be blocked, like how they ban people from twitch chat if they’re making the creator uncomfortable. Boundaries are on a personal level, not a proper transaction like how modern mcyt creators and fans seem to think it is.
Meanwhile, there are things fans can do to help creators with their boundary setting that isn’t fandom policing. There’s a long-standing tradition with rpf-adjacent fandoms where the fans make statements at the top of their fics or in the captions of their art saying something like, “[Creator] DNI!!” While DNIs are really kinda just proven not to work, it’s a phrase creators can filter out and block.
It’s give-and take. Fans should respect their creators’ boundaries. If a creator says they’ll block you if they see you post something they’re uncomfortable with, that’s literally fair on their part, and you should do what you can to keep their online experience safe. But, for that to happen, the creator needs to realize that their boundaries can’t control people, and there needs to be some wiggle room in the form of fan boundaries like tags and such.
But, really, in the end, a boundary is a personal thing. You the fan block out specific tags on ao3 or tumblr that you don’t want to deal with, and that’s setting a boundary to protect yourself. Creators setting boundaries should be doing the same. They should be curating their own online experience the same way anybody else does; they might be celebrities, but they’re fundamentally just people online just like you and me.