Swashplate
I went from First Officer 747 to Captain 757/767. It is taken as read when approved for command training that you can fly. Also when new to type and signed off your first few weeks on the aircraft you are never paired with an FO inexperienced on type.
It is hard work changing seats and type but by no means overly demanding.
I think it would also be fair to say that progressing from new PPL to more complex single engine types to twins to turbo-props to jets each conversion is made easier by the steadily increasing level of experience at each stage.