[faeyanpiraat]

Go into the "Do not disturb" settings, and you can find an option for that there.

Having DND enabled all the time could have unintended side effects though.

[hurricanetc]

Ah. I had not considered using DND for that purpose. Thanks!

[swat535]

Actually there is now a silence unknown caller options if you have an up to date iOS https://support.apple.com/en-ca/HT207099