If you are a very very experienced copilot and flown multiple heavy EFIS aircraft in a variety of flying environments around the world, what does a command course really teach you.
We all know about the hard skills and then there is the non-tech soft skills but what else is taught?
As others have said, you will (or should) be taught:
to handle the aircraft from the left-hand seat;
to develop a sound decision-making framework;
that when making a decision, you have to balance the requirements of the regulator, company, passengers and crew;
about your responsibilities (both legal and more general) to the four entities mentioned above;
about what support is available to you from within the company; and
which different channels of reporting are appropriate.
As you are experienced, you will be expected to arrive for the course with a sound knowledge of various subjects, including but not limited to:
company fuel policy;
airfield operating minima;
Flight Time Limitations regulations;
your aircraft type; and
your route network, including any 'difficult' destinations.
During the course you will be expected to demonstrate that you have learned the material presented and that you can operate to a safe, repeatable standard, in accordance with the provisions of the Ops Manual, adopting a pragmatic approach where applicable.
What they are looking for is a 'safe pair of hands', who can get along with flight and ground colleagues and deliver a safe and punctual operation, with an appropriate level of customer care and focus on business issues, as they arise. In other words, would they want to send their family on a flight with you on a dark and dirty night?