Can I use Apple Pay to purchase stuff on games

You can link Apple Pay your Apple ID purchases, and purchases made through the App Store in games will use Apple Pay.

There are several ways to change the payment information for your Apple ID.

In Settings, tap your Apple ID at the top. Then tap Payment & Shipping to update your payment information.

In the App Store, tap your profile picture at the top right, tap your Apple ID, then tap Manage Payments.

You can also tap this link directly on your iPhone, iPad, iPod touch, or Mac to manage your payment information.

Change, add, or remove Apple ID payment methods - Apple Support