The graphics chipset will actually detect this and handle it as though you hooked up an HDMI cable.
People complained continually that Apple had gone USB/lightning/Thunderbolt instead of standard USB-C. Now they implement the standard and people complain that the standard is a clusterfuck...
This whole ranting start to look a bit unfair.
Sigh...
I've been watching old SJ presentations (1990-2003) lately and I long back to the time where general purpose personal computers, fully capable of tapping into the machine and creating with it whatever you want, was at the forefront of industry efforts. Updates twice a year. Moore's law in full force. Exiting times those were.
Touchpads generally work perfectly out of the box, with any Linux distribution that uses libinput instead of one of the older drivers. HiDPI screens also tend to work perfectly out of the box, though you may wish to tweak them to your tastes. (For instance, I don't want to treat a 1440p screen as 2x 720p, I want to treat it as 1440p with only slightly enlarged fonts.)
1440p represents the one case that integer scaling doesn't quite handle right, because you don't typically want it to scale 2x (showing the same amount of information as a 720p screen), you want it to scale roughly 1.33x (showing the same amount of information as a 1080p screen). So, on a 1440p screen, I disable the automatic high-DPI scaling (which does make the display readable, it just shows less information than I'd like), and use other mechanisms to scale by 1.3x.
For example, if you need more space on a 5K iMac than the default 1440p@2x, you can have macOS render everything at 1800p@2x off-screen, then downscale it to fill the screen.
The UI looks like this: https://support.apple.com/en-us/HT202471
I think it can be done with xrandr, but IMHO it should be a built-in option in GTK-based desktops too.
I don't think that would work well with Linux expectations for rendering, such as crisp edges for fonts; if you like Apple-style rendering of fonts and other UI elements, it may work better.
I'd rather see everything rendered for the display resolution I have, and just scaled at a non-integer factor.
your sibling comment said something totally different... (no mention of audio.)