Unauthorized charges on Apple Account

The first step is to figure out what the charge is for and if it is one being managed by Apple. You do that by reviewing your Purchase History:

View your purchase history for the App Store and other Apple media services - Apple Support

There are many reasons why you will see a charge and they are authorized. Note that for a charge to be initiated on your device, it requires double clicking the side button with the amount showing on the screen, followed by verification with FaceID or Passcode. It is not something that can be done by accident.

• If you started a free trial and did not cancel at least 24 hours before the trial period ends, you will see a charge for the subscription that is also visible on the authorization screen when the side button was double clicked.
• If you are the Organizer of a Family Sharing plan that uses Purchase Sharing, you have authorized other members to make charges to your payment method.

If the charge is due to a subscription managed by Apple, make sure to cancel it here:

View or cancel app subscriptions on iPhone - Apple Support

You can try and request a refund for a charge managed by Apple, but in most cases all transaction in the App Store are final. At times, Apple may offer a compassionate refund, but it should never be expected.

Request a refund for apps or content that you bought from Apple - Apple Support