How do you add an Apple gift card
How do you download an Apple gift card to pay for iCloud
iPhone 7 Plus, iOS 15
Question marked as
Top-ranking reply
You redeem gift cards onto your Apple ID, and then their credit balance is automatically used when you make purchases or subscriptions are billed.
click here ➜ How to redeem your Apple Gift Card or App Store & iTunes gift card - Apple Support
This does not preclude the need to have a valid payment method on file, or verify an existing one if a payment was unable to be made to it. It just causes the actual payment method to come out of the gift card balance first.