iCloud backup
How can I backup my iCloud without using Wi-Fi
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You can backup to iCloud without using Wi-Fi by using 5G cellular in some circumstances. See the following from Back up iPhone - Apple Support
Note: On models that support 5G, your carrier may give you the option to back up iPhone using your cellular network. Go to Settings > [your name] > iCloud > iCloud Backup, then turn on or off Backup Over Cellular.