Back up your phone before it goes missing
A recent backup can make replacement less painful if a device must be erased or never returns. The backup route differs by platform and data type.
What to do
First, check
Check the last successful backup date, not only whether the feature is switched on.
Then
Run a backup and verify the categories you need, such as photos and app data, in official settings.
If it’s not that simple
Backup enabled is not backup verified
Recent successful backup
Check its time and supported data categories.
App-specific local data
Review that app’s backup/export method separately.
Restore not tested
Do not promise every password, chat or file will return on a replacement phone.
Good to know
No backup covers every app or locally stored secret; review provider-specific exclusions.
Official source
Apple Support · back up iPhone