iCloud backup
How do I lock my iPhone screen for backup
iPhone XR, iOS 15
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Not sure what you are asking. We assume that you already have adequate storage space on iCloud. The iPhone's screen will normally lock after a few minutes of inactivity.
iCloud backups occur automatically every 24 hours when the phone is plugged into power and on Wi-Fi........unless you are doing manual backups only.
If the phone is plugged into the charger, the screen will lock automatically after a few minutes.
How to back up your iPhone, iPad, and iPod touch - Apple Support