Find the icon on your home screen—it’s the blue icon with a white "A." Tap it to open the store. 2. Find Your Desired App
If you see a Cloud icon with a downward arrow, you have previously downloaded the app and can re-install it for free. 4. Authenticate with Face ID
Since you are using an iPhone X, the system will use to confirm the purchase: A prompt will appear at the bottom of the screen.
If you haven't set up a payment method yet, you can do so by going to > [Your Name] > Payment & Shipping > Add Payment Method . This allows you to link a credit card, debit card, or PayPal account to your Apple ID.