is it possible to backup iphone 12 to an external hard drive?

Yes.

1. Connect your iPhone to your Mac with a Thunderbolt cable.
2. Click on the desktop and then press Command+N to open a new Finder window.
3. Your phone should be listed in the left hand column. Click on it.
4. If necessary, tell the Mac to trust the device, then tap Trust on the iPhone and enter your phone's six digit passcode.
5. A screen will appear on the Mac with various options. Your main focus is near the center:

1. Click Back Up Now to create a new and current backup of what's on your phone.
2. When it's complete, click Manage Backups… .
3. A list of your iOS device backups will appear.
4. Right click on the one you just created with the current date and choose Show In Finder.
5. The folder where the Mac keeps your iOS backups will appear. Locations is:

/Users/your-user-account/Library/Application Support/MobileSync/Backup/

In the Backup folder, you'll find at least one subfolder with the current date, which would be the backup you just made. It will have a very long name of random letters and numbers.

Copy that folder to your external drive. For future recovery from a new Mac, or it's been lost, put that copy from the external back in the same folder location on the Mac so it can be chosen with Restore Backup… .

gweeds1 wrote:

is it possible to backup iphone 12 to an external hard drive? If yes, how do i do it please?

No it's either to iTunes or iCloud. https://support.apple.com/en-us/HT203977