If you have an old iTunes or App Store & iTunes Gift Card, you do not need to "buy" a different card to use it at the Apple Store. Instead, you can follow these steps:
In countries where the universal Apple Gift Card is available (like the United States), you can use this account balance to pay for products on Apple.com or within the Apple Store app . Critical Limitations
In 2020, Apple began merging these into the universal . This "all-in-one" card allows users to redeem credit once and spend it across all Apple platforms—both digital and physical. How to Use iTunes Credit for Hardware buy apple store gift card with itunes
This unified system is primarily available in the US and select other regions. If you are in a country where iTunes and Apple Store cards are still sold separately, you generally cannot transfer funds between the two systems.
Official Apple Support policies state that gift cards cannot be used to purchase other gift cards. If you have an old iTunes or App
Used strictly for digital content like apps, music, and iCloud storage.
Once redeemed, the funds are added to your Apple Account Balance . This "all-in-one" card allows users to redeem credit
Open the App Store or use the Apple Support Redemption Page to add the gift card balance to your Apple Account.