How to know that data is fully backed up or not
how I will come to know that all my photos videos are fully backed up or not.?
iPhone X
Question marked as
If you are syncing photos to iCloud, go to iCloud.com/Photos using a computer browser to see if they are all there. If you aren't syncing photos to iCloud, the only way to know is to restore a backup. You can't access a backup and only restore certain files, so there isn't any way to check other than to restore the backup.
Backup - Restore your device from an iCloud or iTunes backup