Do factory reset delete everything off Android Samsung galaxy?

Do factory reset delete everything off Android Samsung galaxy? When you perform a factory reset on your Samsung Galaxy S21 (or any Android device), it will erase all personal data stored on the device, including apps, settings, contacts, messages, photos, and other files. However, certain data may remain backed up or synchronized with your Google account or other cloud services, provided you have set them up to do so.

It is true that some data may technically still exist on the device even after a factory reset because a factory reset does not overwrite the data; it merely marks the space as available for new data. This means that specialized recovery tools can potentially recover some of the lost data. This is especially a concern if you sell or give away your device without securely erasing the data.