I had this with some Windows 2012 VMs. All my 2016 / 2019 would open full screen, but 2012 would occupy about 50% of my 1920 x 1080 workspace. Here's how I resolved it. I shut down the VMs in question and edited the VM settings increasing the video ram from 4 meg to 8 meg. (I had noticed that was what the 2016 / 2019 servers were all set to) 😎
I then booted up and the console screen size was the same. I forced the console to open full screen (CTRL-ALT-Enter) then when I came out of full screen I was back to a larger resizable Window. On one of them however I had to go in to the Windows display settings and increased the resolution to 1920 x 1080 (which was not available previously via the VMRC console). Curiously, the ideal setting of 1920 x 994 was not available. (This makes the VM sit in the PC workspace so that the full screen is sat on top of a User's PC task bar, allowing both to be seen at the same time. Running the VM at 1920 x 1080 causes the VM's window to need use of the scroll bar (unless you go in to proper full screen mode for the Vconsole))
So to add the 1920 x 994, I went in to Windows drivers and changed the monitor to be exactly this, 'Generic PnP Monitor'. Even though one of the servers already showed this, I changed it and selected the same and it actually re-loaded a driver and then voilla, 1920 x 994 then appeared.
So the bottom line is, increase the video ram and fiddle with the screen settings once the server boots up. Play with the Windows 'Generic PnP Monitor' driver and also force the VM console to full screen then back again and it should all pop in to life using a combination of these settings / changes.
