Allow built-in apps and features

    You can restrict the use of built-in apps or features. If you turn off an app or feature, it won’t delete it, it’s just temporarily hidden from your Home screen. For example, if you turn off Mail, the Mail app won't appear on your Home Screen until you turn it back on.

To change your Allowed Apps:

 1. Go to Settings > Screen Time.

 2 .Tap Content & Privacy Restrictions.

 3. Enter your Screen Time passcode. 

 4. Tap Allowed Apps. 

 5. Select the apps that you want to allow.

Taken from Apple's Support Page