I'd say the MK3S printer is like 75% plug and play. (For reference, I consider current wireless "2d" paper printers to be 100% plug and play now).
You will eventually need to do maintenance on it, you'll eventually have a clog or a broke part or need to do some slightly technical stuff to fix an eventual problem, but most adults capable of building Ikea furniture should be able to follow instructions and do it.
I'm assuming this will be closer to 85% "plug and play". Things like the "one click print", color screen, WiFi and automatic firmware updates are the biggest nice to haves.
But I don't think they've gotten to the point where you'll have reliability similar to a normal "2d" paper printer, so at some point you'll need to take some stuff apart to unclog it. But that's about the extent of the technical needs I'd expect from this printer.