I use an app called WideProtect. It's not free, but it's also not a subscription. It lets you do exactly what you describe.
As a side note, CallKit on iOS doesn't support wildcard blocking, so WideProtect literally adds all the possible numbers within your specified range to the blocking database. This doesn't impact performance as far as I can tell (maybe calls ring another 100ms after they would normally), but there seems to be a delay of a few minutes after installing for it to show up as a block extension under Settings.
As a side note, CallKit on iOS doesn't support wildcard blocking, so WideProtect literally adds all the possible numbers within your specified range to the blocking database. This doesn't impact performance as far as I can tell (maybe calls ring another 100ms after they would normally), but there seems to be a delay of a few minutes after installing for it to show up as a block extension under Settings.