How to double-click the power button to quickly open the wallet

There’s nothing added to your Wallet app. Add some payment methods. The double click is for when you make a payment/purchase.

The Wallet app is an app not a setting in the Settings app. It looks like this,

If you deleted the Wallet app, just download it again from the Apple App Store.

What happens when you double click the Side Button (power button)? Do you have any payment methods or loyalty cards added to the Apple Wallet app?

Do you need help? because that is not a question