I'll also throw in my vote for Bazzite. I've heard a lot of good things about it in terms of its default included packages and configurations for gaming. It sounds like you may not be advanced enough to mess with settings to make gaming run smoothly, so bazzite would do all of that for you. They have a KDE version. And it is what's called an "immutable" distro where the main systems files can't be modified easily by the user. That will make it safer to those who aren't sure of what they're doing. You can also easily set it up to run Big Picture Mode by default, so if you decide to use that pc more like console connected to a tv, bazzite would be great for that. Like others have pointed out, Bazzite has good support for nvidia cards out of the box, and that's a key feature to note. Bazzite is kinda like an unofficial version of Steam OS that's ready for widespread use and supports a lot of hardware. They're doing what Steam is not ready to do yet.