Warranty transfers automatically. Apple's Limited Warranty and AppleCare are tied to the device, not the person. When buying used, you get the remaining coverage period without any additional steps.
Check before buying. A seller may claim "warranty until 2027," but it may already be expired. Always verify yourself via @ispyware_bot - the report will show the exact date.
Apple-refurbished devices receive a new 1-year warranty from the purchase date. Unofficially refurbished devices do not. Check the Warranty Types: F = officially refurbished.
Unauthorized repair may void Apple warranty. If the device was opened or has non-genuine replacement parts, Apple will deny warranty service. Check the "Parts and Service" section in settings (iPhone 15+) or via GSX.