How do I block children from purchasing apps

Greetings ParentNeedsHelp1955,

Thanks for posting in Apple Support Communities. We're happy to provide you with some guidance.

Prevent in-app purchases from the App Store

"You can use Screen Time to prevent unintentional or unauthorized purchases from the App Store and other Apple services. You can require a password for purchases, prevent certain types of purchases, or disable purchasing completely.

How to use Screen Time to disable in-app purchases

1. To turn on Screen Time, go to Settings > Screen Time, then tap Turn on Screen Time. If you already use Screen Time, skip to step 3.

2. Tap Continue, then choose "This is My [device]" or "This is My Child's [device]."

• If you're the parent or guardian of your device and want to prevent another family member from changing your settings, tap Use Screen Time Passcode to create a passcode, then re-enter the passcode to confirm. After you confirm your passcode, enter your Apple ID and password. This can be used to reset your Screen Time passcode if you forget it. 
• If you're setting up Screen Time on your child's device, follow the prompts until you get to Parent Passcode and enter a passcode. Re-enter the passcode to confirm. After you confirm your passcode, enter your Apple ID and password. This can be used to reset your Screen Time passcode if you forget it. 
  • Make sure to choose a passcode that's different from the passcode you use to unlock your device. Learn what to do if you forget your Screen Time passcode.

3. Tap Content & Privacy Restrictions. If asked, enter your passcode, then turn on Content & Privacy Restrictions. 

4. Tap iTunes & App Store Purchases.

5. Tap In-app Purchases and set to Don't Allow.

Other ways to control purchases on an Apple device

• If children in your Family Sharing group have their own devices, use Ask to Buy to screen and approve their purchase requests.
• If you let children use your device, you can require a password for every purchase.
• To prevent iTunes Store and Books purchases, go to Settings > Screen Time > Content & Privacy Restrictions, then tap Allowed Apps. Deselect iTunes Store and Books."

All the best.