If the computer is modern enough that you’d consider buying it to use, I can almost guarantee that you’ll be fine to run the latest distros. I just threw Arch + KDE on a 14ish year old laptop I found, and it runs so well that I may daily drive it for a while just for the hell of it.
At worst, you may need a lighter-weight desktop environment (DE) than some of the pretty ones you see in screenshots. And those are simple to install and try out.