Been doing that since 2015ish on two Dell 4k monitors. Supported natively by gnome, mate, kde.
Every month I read here that it can’t be done.
Every month I read here that it can’t be done.
This results in a 2560×1440 effective resolution with a bit of blurriness that is acceptable, compared to "native 200%" scaling that makes the controls a bit too large to my liking, or "native 150%" scaling that is hidden behind some "trust me, you don't want to see this" language/button in GNOME.
Things do seem to be slower when it is switched on, which is not the case with the 200% and 100% settings.
This size is very difficult to find these days, presumably because people don’t understand this. Or hardware co. mgmt didn’t.
TL;DR A 4k monitor should be the same size as HD, with 200% scaling. 22” aka 56cm is about right.