Pairing an Apple Watch with new phone (when the old one is dead)

My wife recently went for a swim with her iPhone 6 in her back pocket. She now has a new iphone12 but we can’t seem to find a way to pair her Apple Watch with the new phone. The phone is now saying ‘wrong passcode, go pen the apple watch app on your iPhone go to passcode then tap reenable passcode entry to try again’. I know these things gs are set up to stop people who steal stuff just wiping them but how can I get myself out of this do I can fix my wife’s watch and pair it with her new phone please?