Intel HD Graphics 620

[Yellow Pasque]

You are right, but only partially.

Sorry, I didn't account for old versions of Windows. Anyway, your Asus link ( https://www.asus.com/Mini-PCs/VivoMi...pecifications/ ) doesn't list support for Windows 8, so why are you running that on it?

Official Asus / Intel support response: your video card is only supported by Windows 10.

That contradicts your screenshot where it says "Linux -- Yes". I'm not sure what point you're trying to make here...

At the moment I have Win 8.1 gives the maximum screen resolution of 1280*1024 60Hz, the question remains the same:
what screen resolutions will the Ubuntu video card driver give me?

Since you don't seem to believe what responders are telling you, then you should do as mörgæs suggested, and boot a LiveUSB to see for yourself. You'll get your answer faster that way and there will be no second guessing.

[MartyBuntu]

Linux drivers are not magic.
Yellow Pasque is correct on you being hardware-bound by the physical limitations of your devices.