Not sure about the 21 GCL, but, the 22 GCL Limited I have on order has the Intersection Collision System included as part of a package…the Lux Tech Group II. There is another braking system called the Ready Alert Braking which seems to be different than the Intersection Collision System. That Ready Alert Braking is standard across all trims it would seem.
For what it's worth, I don't think the GCL Limited and below trims have the full collision system. For example, the intersection collision avoidance appears to be on upper trim levels. MY21 had a lot of deletes on different trim levels as well, so I wouldn't be surprised if there were some vehicles without these systems included.
For a radar sensor you can't block it with tape and paper since the radio waves will just pass right through -- maybe aluminium foil or something to create a faraday effect. Snow makes sense in the situation described by BerettaBri since radio waves cannot penetrate water. Overall the goal in this thread seems to be to figure out how to test the system to figure out if and how it works, and I don't think there is a way to do this safely. These vehicles are designed to use the input of multiple sensors simultaneously to detect their surroundings and determine the actions for each situation, if any. It's near impossible to figure out what parameters you will need to have to trigger these systems since we have no idea how the code is written