My issue is that the government shouldn't allow companies - especially tech companies - to become so big to begin with.
There are ways the government can begin to minimize the growth of said companies. There can be taxes based on the amount of MAU, strictly prohibit any acquisition of other "social media" after a certain size, etc.
In my opinion Facebook should be forced to break up WhatsApp, Insta, etc. In addition, the new broken up Facebook organizations should be taxed heavily (call it a network effect tax, that's progressive and highly de-incentivizes being so huge).
Alternatively, the government could just deem certain internet activity "marked" and make it so all "marked" internet activity to require payment. This would include pornography, social media, etc.
That being said the challenge would be creating a reasonable definition of what "marked" includes.