You cannot transfer gift cards out for cash.
The Apple Gift cards can be redeemed onto your Apple ID, or used in the Apple Store for purchases during checkout, but cannot be refunded for cash unless required by law in your jurisdiction. There is no way to put Aplpe Gift cards into the Apple Cash account. link ➡️ Check your Apple Account balance - Apple Support
If you have Apple Account balance that you can't use
You can't redeem or return Apple Gift Cards, App Store & iTunes Gift Cards, or unused Apple Account balance for cash, except as required by law. If your jurisdiction allows for refund of redeemed gift balances, you can contact Apple Support to request a refund. When you contact Apple, include the following information:
Your Apple ID.
The refund amount.
Your current shipping address.
See here to turn on Apple Cash if you are in the U.S. and at least 18 years old: link ➡️ Set up Apple Cash - Apple Support