Trying to heave a massive opponent off your body seems like it would require an endless amount of pure strength, but with the right technique, you can create space and stop their side control from squishing you.
David Morcegao of Invisible Jiu-Jitsu has a (relatively) easy way to escape this dreaded position, and if you practice it enough, even that heavyweight won’t be able to keep you down for long. Give it a try!