Ignoring the ethics of boundaries or the morals of limiting creative expression or anything else, setting rules about what people can and can't do with your characters just doesn't work. It cannot and will not accomplish what you want, and it will create a bunch of new problems.
Theoretical goal of banning things you find uncomfortable as a CC:
Bad things you don't like will stop being made and existing about you/your character.
Actual outcomes of banning things you find uncomfortable as a CC:
Bad things you don't like will Still Exist.
Subsets of your community will harass & abuse other fans. Trolls will make upsetting bait content that devoted fans feel a duty to engage with & fight against. Well-intentioned fans who don't know the rules exist will break them and get yelled at. People will arbitrarily interpret rules to bludgeon other fans' headcanons & send hate campaigns after each other. This WILL happen, no matter how many times you caveat with 'but don't harass anyone': You have issued an edict whose only enforcement mechanism is harassment.
Some of the fans who are most viciously defensive of your rules will still create stuff you find uncomfortable. Life finds a way. If you ban peanut butter, the fandom will create a series of intricate excuses as to why ground peanuts with sugar added is totally a different thing, and moreover how dare you imply they would break boundaries. The stuff you dislike won't stop being made, it will just be mislabeled and harder to avoid.
Artists will inevitably make cool shit that technically breaks your boundaries but Is Cool. Engaging with it will get that artist harassed for ignoring your boundaries (even if you say this one is fine).
Less people will engage with your work. You will have a smaller audience and much more limited free advertisement.
Everyone following the rules will create a constant need for judgment about things at the edge of your comfort zone. 'Ask for permission' means you have given yourself a part-time job arbitrating to strangers on whether it's okay to draw you mad at another minecraft guy.
More earnestly: By and large the people who are most online, who take boundaries seriously and actually care about seeking permission, are teens and very young adults. That's who you're setting rules for and telling that they can't depict certain things. The kinksters and smut writers and grown-ass adults are generally going to be unaffected, because their self-esteem doesn't hinge on the approval of a Twitch streamer.
Genuine question: Do you want to have to stare at an ask on Tumblr and consider whether to give permission for some 14-year-old to write a fic about your character self-harming or having cancer or being sexually assaulted? To say yes or no, while knowing that this person is probably asking not out of prurient interest, but because it makes them feel a little less alone to imagine an older, stronger character going through what they are?
That is the actual effect of setting those rules.
(The better boundary, btw, is 'I don't want to see things that make me uncomfortable': it's still not perfectly enforceable unless you entirely abstain from the internet, but it is much more actionable than 'make that stuff stop existing'. Having a dedicated 'don't look' tag blocked solves a lot of problems. Another strategy would be letting friends/trusted fan-acquaintances vet the best work and send it to you to gush about, rather than scrolling your tags at random.)
At some point if you tell stories in a public setting, people will want to pick up and play with those characters too; if you can't handle that (and a lot of people can't, this is not a value judgment) then the role of 'professional public storyteller' may not be for you.
