Windows certainly can display higher than native resolution on an LCD screen as proven via this random experiment where I have two displays with different resolutions while in Duplicate Desktop mode, where the smaller screen displays a desktop originating from the larger screen.
How to achieve this Duplication downscaling trick on two separate desktops (Extended mode)?
Notice the screenshot of Display 1 below, where it says
Desktop resolution 3840 x 2160
Active signal resolution 1920 x 1080
HP ProBook 650 G2
Intel HD Graphics 530
Display 1: BuiltIn 14" display @ 1920x1080
Display 2: External 24" DELL P2415Q @ 3840x2160
Attempt at making a screenshot via PrtScr of whole screen, or Win+PrtScr or via "screen snipping" results in this weird downscaled FHD desktop, while the image resolution remains UHD.
I had to take photographs instead of screenshots, because of the weird desktop downscaling as shown in Screenshot/Perceived comparison.
I appreciate your concerns that the result would look shite, (in fact it is possible to read from it without difficulties,) but this is exactly what I am trying to achieve for years and I am desperate already. I will be using the 4K screen for main activities and the UHD-downscaled-to-FHD screen for browser feedback while developing.