Add Apple Credit Card to iPhone wallet

>>Add Apple Card to your iPhone

1. Update to the latest version of iOS. 
2. On your iPhone, open the Wallet app.
3. Tap the add button.
4. Tap Add Card, then Follow the steps to select Apple Card. If you're asked to add the card that you use with your Apple ID, cards on other devices, or cards that you’ve recently removed, choose Apple Card.

After you add Apple Card to your iPhone, you can request a titanium Apple Card in the Wallet app.<<

How to add Apple Card to your Apple devices - Apple Support