I know 7 ruled back in the day but why are you still on it? For retro gaming? if 10/11 are privacy issues for you, Pop Os (free Linux distro) can play just about anything and doesn't have the security issues or hardware limitations that 7 has now that it's out of service.
It's been a while, but I'd imagine you could get away with using an nvidia gt 1050 or lower, even then windows 7 I think is still supported for most software / games, so you probably could use some of the newer models as well, I'd check to see if they support windows 7 and of course make sure the port on the motherboard can support the connector.
I believe there are Windows 7 drivers for newer Nvidia cards including RTX 2000 and 3000 series but with such an old and extremely low RAM, it is not worth putting in a modern gpu unless you upgrade your processor. I think you are better off with a Nvidia GT 1030 unless you upgrade. I also tend not to upgrade to newer versions of Windows until I know it is safe and stable but Windows 7 is extremely outdated. You really should think about upgraded both your pc and Windows. The benefits definitely outweigh the disadvantages.
If you can put more ram in your computer that probably is your bottleneck. 2gb for win 7 is low. Physically you might be able to put a modern gpu in your case, but you'll probably have to update your power supply. You will have a fast video card but your cpu will be your bottleneck and not be able to pass info to the gpu fast enough. Then you're on a cycle of upgrade this then that. Miuht be better to just get a new system.
With only 2gb of normal RAM, it's unlikely that upgrading graphics will net you that much performance since the rest of your system is probably bottlenecking.
