One of the best new settings that come with iOS 13 is the ability to silence calls from unknown numbers. This can be found in settings -> phone just like the screenshot below:
Granted this is not much use if you expect calls from numbers not in your contacts, or if you are worried about people trying to reach you in an emergency. But for those like me who rarely get calls and is sick and tired from the constant robocalls, this is an awesome solution.
I’ve had it enabled for a few days now and it’s silencing close to 5 calls a day. I consider that a win.