How can I prevent unauthorized charges by Apple?

Apple did not steal your money. What did you find out the purchase was for, that is easily done by viewing your purchase history. Purchases on your device are only made after double clicking the side button with the amount showing on the screen, followed by verification with FaceID/TouchID or Passcode. How did you determine that was done?

If you signed up for a free trial and did not cancel the charge at least 24 hours before the trial period ends, then you have also authorized the subscription that you signed up for and that is detailed as well on the screen before you double clicked the side button.

Check other devices that you have allowed to use your account with your Password. This is listed by going to Settings > [name on top], and scroll to the button. You can remove the devices there if you wish and change your password.

Now that you know that Apple did not steal your money, how about providing the details what you did find out and how the charge occurred. With that information, we can provide additional steps to take to prevent it from happening again. If you do not know how to check your purchase history or view your subscriptions, follow up and we can provide those links.

You may be able to request a refund, but in most cases all transactions in the App Store are final, simply because it cannot be done by accident and the verifications required show that it was you or someone you have allowed to use your device. At times Apple may provide a compassionate refund, but it should never be expected.