maybe it’s not very clear for it to be a button, but you don’t see “ADD A NUMBER” as in those screenshots?
→ Call forwarding, waiting and blocking
’Blocked numbers’ settings page opens, here you can tap ‘ADD A NUMBER’ to manually input a phone number …
you can block anything from the call history after being harassed… but whenever it happened for me there were multiples of and a pattern emerged, so I had to use the YACB App anyway.
Only accepting calls from numbers in contacts is another solution