I've tried a few apps including better display to find a better resolution for my portable 16 inch monitor. It does allow you to set the resolution you want, but it's a bit blurry.
No way to really fix it, it's just another Mac shortcoming. Using resolution to scale the UI is not a compromise, it's a mediocre workaround.
I'd call that a shortcoming of all hardware that isn't retina resolution, but I know how that sounds to anyone who isn't bought into the ecosystem.
To be clear, I criticize the hell out of the company on things that I think are truly bad. Their app store policies are a disaster. I get that gamers want framerates over resolution. I'm not a gamer and want the other thing.
It's a shortcoming of the software. Apple could claim it's a third-party issue if they didn't support arbitrary external monitors, but they do. As such it's entirely reasonable to expect a fallback solution for third-party displays that Just Works.
For my money, Windows is a terrible operating system but it embarrasses Mac and Linux thoroughly in this regard.
mac users love to repeat this but it's just nonsense. if you can plug another non-mac computer into the same display and get crystal clear, correctly scaled UI then the screen isn't the problem, the computer is.
No way to really fix it, it's just another Mac shortcoming. Using resolution to scale the UI is not a compromise, it's a mediocre workaround.