It was pretty informal.
At Toronto Pearson, when you're coming through arrivals you're directed to a separate line/room area where you just wait your turn. The CBSA agent calls you up to the counter and checks over your COPR, passport (and visas you may need to have to access Canada) and any supporting docs and just casually asks questions about your visit, where you're heading, do you have a place to stay and in my case, handed me the medical surveillance forms (which I don't need to worry about until I land properly and have a permanent address in country).
Things can be more complex if you come from countries where there's a track record of people being, shall we say, less than honest about their intentions... I'm from the UK and didn't have any issues but while in line there were 3 south Asian travellers and one Chinese national ahead of me who were getting the holy hell grilled out of them! Pretty sure at least one of them was about to be bounced out the country... didn't seem able to answer a single question with a clear straight answer.
They have access to all your forms and data that you submitted in your application and any backoffice flags that may be applied to your application. Just be calm, polite and honest.
