How can i extend my warranty

See this About continuing your AppleCare+ coverage for iPhone, iPad, and Apple Watch - Apple Support However, you would have had to already purchased AppleCare+ within the original confines before this would apply. In other words, if you purchased AppleCare+ within 60 days of the original purchase of your device, you could see about extending it with the information in that support document. However, if you did not purchase within 60 days of the original purchase of the iPhone, you could not purchase it now.