If on iOS you can set category or individual time limits under “Screen Time” in settings. Really useful and it’ll give you stats for whether you are doing worse or improving. 

I’m certain there are options in Android and Graphene or the like, but I’ve not used them because they are secondary devices for me. Maybe nostr:npub1ajv7m32k0cpgzha32qszsh304qusjvwwmavus0ttktzldms4xzusuftppj knows