I just use the "Silence unknown callers" feature in iOS - It's a godsend. I also noticed after a few months that I actually have a lot fewer unknown calls now. (You can look to see missed calls)
For example I was dropping the dog off at the vet and I was in the parking lot waiting for our turn (lobby closed for social distancing). Their call to me was silenced even though I had called the same number minutes earlier to check in.
So now I’ve moved to aggressively adding numbers to my contacts for any business I interact with (auto dealership, vet, pet groomer, etc). Which isn’t terrible but it feels like this could get smarter at some point.
Not answering unknown numbers not only saves you the trouble of getting them but also results in fewer robocalls over time since you do not answer.
It's a great feature. Or at least it was until recently. Local health departments say it's killing their ability to do contact tracing, as many people don't listen to unknown voice mails, either.