I use Yet Another Call Blocker. It has a custom block list you can use to block a specific number.
The block list also supports wildcard characters, which is my favorite feature! I use it to block swaths of numbers (much of my spam comes from the state I used to live in, so I block those area codes).
The app has not been updated in long time, but the database is still updating daily for me, and the app still works on Android 14. Can't tell it will continue working in the future...
Looks like the F-droid version is way behind, because you can see on their GitLab page that the project is still maintained. It'd be best to get the app directly through GitLab I suppose, or add an F-droid repo that has a more up-to-date version.
Been using NoPhoneSpam. While it won't automatically block any numbers, it will cancel incoming calls not matching its filters. Only issue is that, some times, it takes a few seconds for it to recognize not passing calls, but I think it happens when the phone is under a higher load and the system starts lagging a bit, like when downloading bigger files and playing games.
If you're in the US and on a carrier that supports stir/shaken and voLTE, Carrion can block (or silence) calls that fail verification. It can also block calls from a block list.