Is there a way to quit Applications from the Task Switcher? I have Cover Switch enabled and would like to be able to close Applications from this view. This habit formed during my Mac OS days and very much miss the convenience of walking through Applications and quickly quiting the ones I no longer needed open.

Is there a way to do this in Plasma?

Not with the task switchers it seems.

But the "Present Windows" effect should do what you want, that can be activated by pushing the moise pointer into the top-left corner of the screen or via Ctrl+F9 (shows all windows on the current virtual desktop) or Ctrl+F10 (all windows on all desktops).

And you can close the active window via Alt+F4.