virsh edit Windows10
- Navigate to the
<video>
section and change it to the following one:
<video>
<model type='qxl' ram='131072' vram='131072' vgamem='32768' heads='1' primary='yes'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</video>
- Start the VM and install the "Windows guest tools" from Spice Space: https://www.spice-space.org/download.html
- Shutdown the Windows 10 VM and activate "Auto resize VM with window" via the "Virtual Machine Manager" -> open the VM -> "View" -> "Scale Display" -> "Auto resize VM with window" (https://unix.stackexchange.com/a/589766)
- Start the VM. It should now automatically be scaled to the max. possible resolution.
Thanks for this information!