I have tried. It is very difficult. In fact tiktok and Instagram have so many domanin names and IP addresses that it is hard to list them all and block them.

Blocking the main domain would prevent you from accessing the web site, but the mobile app would work. Then you can block the api and stuff, but clients already connected would still work because they rely on the CDNs. When you block a good bunch of the network, the app would just feel Brocken, not blocked. When users keep reloading they will find a CDN you have not blocked yet. Also, they will still get notifications because they are pushed via Google services. They won’t see them in the app however.

So you just need to monitor the logs to keep block tiktok domains that pop up.

If you can block via regex or joker chars (*) then, it would be eisoer for you.

You can look up domains list of tiktok on the internet f9r a good start.

For my experience, I just managed to make tiktok and Instagram broken enough to frustrate the users and discourage its use over the network.