Just want to wrap up this thread by saying there is no single perfect solution here but a combination of tools really does work. Here is the full setup that covers most situations:
- Block the app through Family Link or Samsung parental controls
- Lock down the Play Store with a PIN and content rating filters
- Block TikTok at the router level for home Wi-Fi
- Set up TikTok Family Pairing if the account already exists
- Disable sideloading from unknown sources in Settings
Each of these alone has a workaround but together they cover most gaps. The goal is not to make it impossible, it is to make it inconvenient enough that your child just gives up and does something else. Most kids will.
Good luck to everyone dealing with this. Parenting in the digital age is genuinely no joke 
