Use current Android settings
Google's current Android guidance describes device backup through Google settings and notes that not all apps can back up or restore all settings and data.
Know the backup account
The Google Account selected for backup determines where supported device data is associated.
Photos may use a separate service
Google Photos backup is separate from some device-backup functions.
Check before resetting
Verify important files and app data rather than assuming the device backup includes everything.
General consumer technology information only. Interfaces and menu names change. Before resets, reinstalls, storage changes or other major actions, verify that important data is backed up and use current manufacturer/service-provider instructions.