To control in-app purchases on your iPhone or iPad, you can use Apple’s parental controls to restrict or allow them as needed.

Here's how:

1. Open the Settings app on your device.
2. Tap Screen Time ➜ then Content & Privacy Restrictions.
3. Enable restrictions if they’re not already turned on.
4. Tap iTunes & App Store Purchases.
5. Select In-app Purchases and choose either:
   • Allow – to enable purchases
   • Don't Allow – to disable them

For step-by-step instructions, visit:
👉 https://support.apple.com