What visa do you have? If visitor you can’t enter Canada right now unless you have immediate or extended family, and then you also need written authorization to travel. You can’t board a plane without it.
As others have said, you will need to be holding the right documents (e.g. valid visa) and authorizations / exemptions to allow you to board the plane due to the pandemic.
Sorry, I didn't mean to scare you, What I am trying to say is, you can claim to be protected in Canada at the Airport, but you have to claim after you are already cleared your entry because sometimes it is a risk to make your claims at the point of entry, it is better to make your claim inside Canada! meaning once you land and you are inside Canada then fill in the form and get it to your nearest IRCC
