How to extend my warranty for iphone xr

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If your phone only has the original warranty you can add AppleCare+ within the first 60 days after purchase. If it is beyond the 60 day limit you cannot extend the warranty.

If you purchased AppleCare+ when you got the phone or within those 60 days you can extend it when the original AppleCare+ expires, as explained in this Apple support article—>About continuing your AppleCare+ coverage for iPhone, iPad, and Apple Watch - Apple Support