yes, for 21 days , then you must move, I crown land camp often there is an awesome MNR web sight where you can locate these spots, You must remember to take your garbage back out with you or burn it .
Here you\’ll find lots of info for backcountry camping, https://www.ontario.ca/page/camping-crown-land
Above was a broken link, I’m also interested in crown land camping, but have only been once to a spot with friends that was a drive in spot. You might also have to be mindful of potential logging operations or hunting during hunting season on some tracts of crown land, but here is a link with some info. https://www.ontario.ca/page/camping-crown-land