Comment by drdexebtjl

Assuming you're using a filesystem that supports it like ZFS, Btrfs, XFS, etc, it's as simple as:

  cp -R --reflink=always /path/to/source /path/to/dest

On macOS with APFS:

  cp -R -c /path/to/source /path/to/dest

That's it. You get a copy that only stores additional space for metadata, not the files themselves.