go to "new game", then on the web version you can switch the type of game from standard to most variants that are popular
Why arent more people playing freestyle chess?

yeah they are organizing quite a few online and over the board tournaments but overall support is pretty low for us casual online players
Just got into it recently and it has been a new source of inspiration to play more chess really, openings are completely thrown out of the window and there are better chances of getting a more complex and interesting game, yet so few people play it. I guess chesscom doesnt have good enough support for it for now, but they should definitely invest heavily into it. Its not simply a weird variant, but a great new way to play and learn the game