Connect your iPhone to Wi-Fi
Go to Settings
Tap your name at the top
Tap iCloud
Tap iCloud Backup
Turn on Back Up This iPhone
Tap Back Up Now
Keep your iPhone connected to Wi-Fi until the backup finishes
To back up to a computer, connect your iPhone to a Mac or PC
On a Mac with macOS Catalina or later, open Finder
On a Mac with macOS Mojave or earlier, or on a PC, open iTunes
Select your iPhone
Choose Back Up Now
To encrypt the backup, select Encrypt local backup and set a password
Wait until the backup is complete
Check the date and time of the latest backup in iCloud Backup or Finder/iTunes