I have an iPhone XR and not able to upgrade to iOS 15.1 ando not able to pair my new apple watch series 7
How to upgrade to software 15.1 on my iPhone XR I have tried many times
iPhone XR, iOS 14
See: If your iPhone, iPad or iPod touch won’t update - Apple Support
and see “If you can't set up your Apple Watch or you get an error message“ on this page: Set up your Apple Watch - Apple Support