I did the following experiment on a 21.5 retina display:
Open Pages, and write some lines with Courier New at point size 4, 3, 2 and even 1.
Use default screen 2K High Resolution and then set view to Actual Size
Use extreme 4K Resolution and again set view to Actual Size.
The typefaces with 3 and 2 points are readable in both modes, but they seem better in 4K. How is this?
I mean, is not "2K Retina" supposed to present a default resolution of 2K but render objects at 4K? Just to be sure, "2K low resolution" seems to have a worse rendering of the 4, 3 and 2 typefaces. But 4K seems the winner. It is just my bias, or is it a fact that it renders better than 2K?