The first step to determine that is by looking at your Purchase History to see what the charges are for:
View your purchase history for the App Store and other Apple media services - Apple Support
You can see if there are other devices using your Apple Account by going to Settings > [name on top], and scroll to the bottom to see the list of devices.
If you are using Family Sharing and have allowed Purchase Sharing, then purchases from other members are authorized to use your payment method and they may appear under their Apple ID.
Please update with the additional information or screenshots if you wish to determine what the charges are for. You will then be able to determine if you have those apps on your device and possibly if someone else is using it requiring you to change your Passcode. A purchase on your device can only happen when the side button is double clicked with the amount showing on the screen followed by verification with FaceID/TouchID or Passcode. That is not something that can be done by accident.