I have a new business-class laptop and Windows 10, with an external monitor connected via HDMI.

Both monitors (i.e. the laptop's and the external monitor) are 1920x1080 but the external monitor is physically bigger than the laptop's.

When I drag a window from one monitor to the other, the window's contents resize: the size of text is physically about the same on both monitors, and the larger monitor is able to show more text within a window.

My question is, does Windows really know the physical size (and/or DPI) of the external monitor, or is it only guessing?

More specifically, if I were to connect a slightly larger external monitor, would it be able to show slightly more on the larger window ... or would it only show the same content/layout but slightly bigger text?