A lot and it cannot be just captured in a single answer. I will try to generalize some based on my experience
The complexity will depend on number of factors like following (a sample list)
I work as a design verification engineer in chip design/VLSI industry.
In short, this means I simulate the functional aspects of a chip during design and before it is manufactured. (If u want to know more in depth you can read)
The hello world for us design verification engineers is to make sure clocks are toggling and reset...
This week, I got an invite to talk to a batch of final year Electronics Engineering Students who was undergoing a 4 week internship training as part of curriculum.
The students have completed 6 semesters of their graduation program and completed course work on Semiconductors, Digital Electronics, ...