There's a lot of research out there on the appropriate amount of time for social media use, particularly for young people. That is something they should be discussing with their parents or guardians. It may be different for every family.
We take screen time use very seriously. As I mentioned, we have a default 60-minute screen time limit that applies to all users under 18. If you spend time on TikTok after a certain hour, every once in a while a video will come up suggesting that you take a break.