How to block all phone numbers from a specific device on iPhone?

Sorry, but this is a user-to-user support community. You are not speaking to Apple. No one here can do this. It also is not feasible. The device isn’t what is blocked, the contact point is. You can offer Apple feedback here: Product Feedback - Apple

A couple of options:

• When a new number is used to reach you by that specific person, add it to the existing contact record.
• Better yet, don’t pretend that blocking is effective (it isn’t). Try the privacy measures available on the phone: Screen and block calls on iPhone - Apple Support

That would not reasonably be possible.

Your phone can not identify the specific device that's calling you. It can only identify the number that's being provided by caller id on the cellular network.

As has already been suggested, if you feel you're being harassed, contact law enforcement.

That's likely a civil matter for police and the courts, as a harasser can use other devices.

VoIP just happens to be cheap, but somebody so inclined can scrounge other phones.

Victims' rights organizations can potentially have some suggestions for these cases, as well.