About the only way to add into the DE a way to assist the zero point user is a video tutorial option that comes up on boot. Then there is also the possibility of a little pop up informational dialog that comes up whenever an active button is hovered over.
If KDE wants Plasma to take over as the dominant DE then the best way forward IMO is to somewhat emulate what Zorin and Mate have done. In basic settings the user selects a UI under Appearance that imitates Windows, Mac, Gnome, Plasma (as it is now), Deepin, etc. It would in fact be great if a UI could be imported like themes. Then after a UI is selected a user is free to go into the granular settings to really tweak it.