Iphone 13 won't pair to Apple Watch 2

I just received this Apple Watch 2 as a used gift. Watch has been wiped and reset. When I go to pair it with the iPhone 13, it goes through the pairing process, but then says that the Apple Watch needs an update, but the iPhone needs to be updated first. iPhone is completely updated to 15.5. So I'm stuck.

Any ideas on how to get the watch updated so it can pair? Thanks.