Unable to pair new Apple Watch Series 10 with my iPhone 14 Pro Max

Saying that it won't pair doesn't really tell anyone anything.

Please explain exactly what happens when you attempt to pair the watch and phone. Give a very detailed explanation about what occurs on both devices.

M1 Mac mini, macOS 15.5;  Watch, series 10 GPS-only, watchOS 11.5; iPhone 16, iOS 18.5; TV 4th Gen, tvOS 18.5 HomePods, audioOS 18.5

Did you already have a look at the troubleshooting mentioned in this article?

If you can't pair an Apple Watch with your iPhone - Apple Support