Prevent iTunes & App Store purchases

 

 

You can also prevent your child from being able to install or delete apps, make in-app purchases, and more. To prevent iTunes & App Store purchases or downloads:

 

 1. Go to Settings and tap Screen Time. 

 2. Tap Content & Privacy Restrictions. If asked, enter your passcode.

 3. Tap iTunes & App Store Purchases.

 4. Choose a setting and set to Don't Allow.

 

You can also change your password settings for additional purchases from the iTunes & App Store or Book Store. Follow steps 1-3, then choose Always Require or Don't Require.

 

Taken from Apple's Support Page