What is the keyboard shortcut to right click any file or folder?
The way you formulated that question,
I'm guessing you're talking about Dolphin. In that case, you can open the context menu from the keyboard by pressing the ≣ Menu key, which on most keyboards, is situated between the right Meta and Ctrl keys.
So that's what that key does.
Don't you think this is controversial?
You probably mean the Menu keyboard button.
I can't find it working in Plasma. It has to do with Toolkit (gtk/qt).
For example, in Firefox (GTK) you can successfully use Shift+F10