By choosing to require authentication for each payment, you can prevent indiscriminate purchases.
You can set up purchase authentication for each store as follows:
1. Launch the [Google Play Store] app > Select your profile picture at the top right.
2. Go to Settings > Authentication > Choose to require authentication for purchases.
3. Select the desired setting from [Authenticate for purchases through Google Play on this device, Authenticate every 30 minutes].
■ Apple
1. On your phone, go to [Settings > Your Name > Media & Purchases > Password Settings].
2. For purchases, choose the desired setting from [Always Required, Require After 15 Minutes]