Educating your kid about the many possible pitfalls of social media is even more important. They will eventually experience it, are likely already to some degree through their friends’ devices exposed to it. Don’t make the mistake of turning social media into some kind of forbidden fruit, but instead provide them with the tools to deal with it responsibly.
That said, I would still not allow this Chinese psy-ops tool on any device in my household. Other social media is already terrible enough, but TikTok seems to be engineered to cause nothing but damage.