My experience virtualizing Windows 10 on a newerly installed and released Fedora 30 using GNOME Boxes, VirtualBox, and VMware Player, all available for free.
- Make sure your hardware supports virtualization.
- Enable virtualization capabilities in your BIOS.
- Get a Windows 10 ISO from Microsoft's Download Windows 10 page. You may not be able to download the ISO directly from this URL in case you access it from a Windows computer, though this may easily be circumvented by changing your browser's user agent to one of a non-Windows computer. Make sure the ISO has been downloaded successfuly after it has finished.