Restore a disk
You can restore a volume from another volume. When you restore from one volume to another volume, it makes an exact copy of the original.
To restore a disk image, see Restore a disk image to a disk.
WARNING: When you restore one volume to another, all the files on the destination volume are erased. Before you restore a volume, copy any files on the destination volume that you want to save to a different volume.
Choose View > Show All Devices.
Select the volume in the sidebar you want to restore, then click the Restore button
or choose Edit > Restore.This is the volume that is erased and becomes the exact copy.
Click the Restore pop-up menu, then choose the volume you want to copy.
Click Restore, then click Done.
You can also use Disk Utility in macOS Recovery to restore a volume. For information, see the Apple Support article About macOS Recovery.