When I worked as a systems engineer I was required to turn vaguely expressed concepts into fully fledged functional and safe deliverables on multi-million research projects. The work included electrical, electronic and mechanical design, construction, and verification so it was quite challenging. Which is why in the UK we have Chartered Engineers, who have to pass a tough validation to be so nominated.
The word "engineer" was debased long ago by confusion with "engine". An engineer is not someone who builds, services or runs an engine, it's someone who exhibits ingenuity (same original word root from latin). They may indeed design or build engines, but not just ordinary ones.