When I had one you could force it to 800x600 @ 56hz and it would do 1024x768 interlaced.

With cards from about 2012 upward you start having the problem that not all of them have the DVI-I analog output that just needs a passive adapter for VGA, this varies by manufacturer so you have to check it on a card by card basis.

56Hz or interlaced are eye-melting options. 640x480 works fine (and tbh anything higher would be impossibly small anyway). You can pair it with any video card that supports VGA. I'd be more worried about the software - iirc Windows 7 defaults to 1024x768@60Hz if it doesn't get any EDID from the monitor (and it surely won't from this old beast), at least during boot. To be safe you'd need to run XP on the machine, which would be a bit of a waste with 8GB RAM.

I wish kids would stop referring to these games as boomer shooters. The youngest boomer is 59 only for a few more months, plenty of gen x and millennials were brought up playing these games. It is agreed that it is because of the people that played these at release are "old" that they are 'boomers'. Baby boomers are a specific generation, you can't go calling everyone older than 25 a boomer, it just sounds idiotic.