There are alternatives.
One medium outside central control is amateur radio packet networks. So instead of using a corporate ISP as your internet service, you'd use a chain of privately operated amateur radio stations to transport data. I've never used this, but it's discussed as a kind of fallback emergency data network.
Even in the world of corporate ISP networks, if free speech is squashed there, see what's happened with memes making it through social media filters – there are ways to encode data that aren't evident to the censors. Over time they might get text recognition in images perfected, but there are always new angles.