It'd probably depend on the game, but see if there's any source ports for the games in question. DSDA Doom, for example, adds modern wide-screen support to classic Doom and has heaps of fantastic options for different compatibility levels for different custom map sets. GZDoom is also an option if you want gameplay mods (shame it's so inefficient lol).
You can also see if there's any wide-screen patches for your games on the PC gaming wiki.
I remember back in the day linking 3 computers together, each running a copy of Doom, to get a pseudo VR type setup where the two computers on the sides showed a left and right view of your perspective.
Was a bitch to setup back in the CRT days, and we only did it once, but it was pretty cool. I'm sure a modern computer could handle that on its own now, but I have no idea how you'd set that up software wise.
If you're using Windows, DXWnd has some options for improving the graphics in games. It may not work for every game but it's probably worth checking out.
I don’t just mean DLSS or frame generation as it exists today… I mean completely re-interpreting what is rendered before it’s displayed with complete temporal and deterministic consistency. Given that we’ve seen some demos of the concept in action, and that was over a year ago, I really don’t think it’s far off, either.
Imagine booting up classic Monkey Island, and Nvidia’s AI reinterpreted makes it look like a high-end modern animated TV show. That’s the kind of thing I’m talking about.