How to fix "mount_apfs: volume could not be mounted: Permission denied", on macOS

- Please watch the upper ☝︎ video carefully and follow the steps. (in case the video doesn't work, press on this link) 
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How to fixed this:-
1) Force an External Hard Drive to Mount via Command Line Terminal.
2) mount_apfs: volume could not be mounted: Permission denied.
3) How to make root volume writeable in Big Sur?

The code used in the video: - 
sudo diskutil mountdisk disk1s5