KDE Plasma (KDE) is a well-known desktop environment for Unix-like systems designed for users who want to have a nice desktop environment for their machines, it is one of the most used desktop interfaces out there.
Linux distros usually ship with one main desktop environment, but you can install others without reinstalling the distro. I have Manjaro KDE as my distro, but I also have Gnome desktop installed on it as an alternative desktop, and I can switch between them from the login screen. This is because the underlying Linux kernel across all the distros is the same one. The distros just add their choice of desktop, theming and apps on top.
The key thing is to be sure you install all the dependencies it expects to find, and the linked article below will show how to do that.