That could be a tricky task depending on the app to bock.
For example, I'd love to block Facebook messenger, but that's tcp/443. Good luck with that.
You could look at a layer 7 approach, but it'll take some research on your part, much testing and a lot of router CPU.
Sent from my cell phone. Sorry for the errors.
Alain Casault, Eng.
If I helped you, let me know!