Easy Manjaro virtual machines with Gnome Boxes
Launch Gnome Boxes in your favorite Linux distribution, click the PLUS sign on the top left corner.
On the above pop up box select ( Download an operating system ).

Type manjaro in the search box, click next and you pretty much done, we advise a minimum of 4gb ram for a better virtual machine experience.

Gnome boxes automatically downloads the latest ISO image.
Alternatively you can also have a look a virtualization with Virt-manager or Virtualbox or Vmware.