1) Learning nano/vim
2) Understanding what X window manager is and does
3) Understanding how config files work
4) Editing the appropriate config file to change DPI. Be careful not to do something wrong or you'll mess your system up
So easy my grandma could do it.
If it’s not, you’re welcome to actually point out the configuration files I need to edit. I tried many “solutions”, even edited boot parameters to no avail. According to sources I read, someone without an Nvidia graphics card might have an easier time.
xrandr --output HDMI-1 --scale 0.75x0.75 --mode 4096x2160
Play with the scale numbers and the resolution until you get the desired effect. Can't give a full tutorial here but "xrandr hdpi" should yield helpful search results.I'm not denying it's a pain and Windows/MacOS are miles ahead, but this is how you can get by on Linux with X. I use it daily for work and media, on a variety of monitors.
Edit: Maybe you meant using a native 2x scale paired with downscaling. Interesting, sounds promising.
Most people I know with a legitimate use for a desktop also have legitimate reasons to use Windows or macOS: gaming on Windows, content creation on Windows or macOS (graphics designing, video editing, ...), and MS Office lock-in. The only exception I can think of are developers, but even then, depending on the kind of development one is doing, using Windows or macOS may be the only choice.