Westjet and Air Canada have occasionally tried to be "militant" about bag checks and it's quickly been stopped after customer backlash. I don't see how that changes now, but I'm open to being surprised. Flair or other ULCCs are way more upfront and committed to dealing with it.
Here's an example of when they tried to "get serious" about checking carry on sizes almost 10 years ago.
https://www.cbc.ca/player/play/video/1.3082753