ZDoom

This would be good. As I mentioned elsewhere, the episode menu of a WADSmooshed IPK3 falls off the bottom of the screen for me in full screen at 1920x1200 but when I switch to windowed mode, the menu gets a bit smaller and it all fits.

I think on larger screens, say scale >= 4, the menu should scale one level lower than the screen could take.

This happens because the game calculates the closest integer multiple for upscaling. At 1080 that becomes 1080/200 = 5, and at 1200 it is 1200/200 = 6.

The code doing this is in V_UpdateModeSize - I suppose a CVAR could be added that allows the user to override it. Strictly speaking, the new size you're seeing is probably the right size had your screen been 320x200 playing in DOS. But it could also be argued that the defaults for 320x200 are too big/cramped and most users want something smaller. The text being cut off is because some of the menus got text too wide for the original DOS font size.

Well, the thing is, I recently got a 1920x1200 monitor and compared to the 1920x1080 one, the menu looks huge. Is there a way to scale it down? Some of the settings are off the screen and God forbid that I load something with non-vanilla fonts. The text goes into space. Can't post screenshot because print screen doesn't work in the menu, but to be precise, the "Sprites & Particles" is cut off at the ampersand. "Fullscreen only" is just "Fullscreen".