The consoles are always scaled 2x for my windows 7 guests. Note the dimensions of the image 2880x1620 vs the indicated resolution of the VM screen.
Please report this to virt-manager upstream too and provide a screenshot Thanks
Maybe related with https://bugzilla.gnome.org/show_bug.cgi?id=771293 , but I am not sure
upgrading to gtk+-3.22.4 fixes the issue with enourmous UI elements sizes on HiDPI display and also fixes the issue with 2x scaling
Thanks for updating us.