How to downscale for an external display? I intend to connect my old full HD TV as external display to a mid-2012 MacBook air. 

While being "only" 1920×1080, the TV has 42", so each element would look ridiculously large. So I thought about "emulating" it to be, say, 4k, then downscale the signal to the 1080 the TV can handle.

Is there such a possibility?


MacBookAir5,1
Mojave 10.14.6
Intel HD Graphics 4000 1536 MB
Assuming you want to extend your desktop and not just mirror it:
The Mac does this by default, for more fine grained options go to System Preferences → Screen, a window for the TV will appear, where scaling options is avaliable. For even more options hold down the Alt/Option key while clicking on "Scaled"