There are sooo many tiktok commies. Just search "leftist" or "communist" or other similar terms and watch the videos, liking the ones you like, pressing "don't recommend" on ones you don't (including the inevitable capitalist apologia that will slip in), go to the channels of the people whose videos you like and watching through them, if you like enough then follow them, and go through the recommended people from there etc etc. Comment on videos you like.

Pretty soon, tiktok will make your fyp exclusively commie (in addition to whatever other interests you have).