Ok, this is not going to be a well formulated question, because the concerns behind it are nebulous in my own head.
Some assumptions I have, that clearly inform the question that follows: I believe commercial, state, and others have sophisticated methods of influencing what I see on social media and thus, in part, what I think. I also believe that someone more willing to believe in the types of conspiratorial beliefs I’ve just expressed are more likely to be manipulated by information they’re exposed to. And, yes, I fully appreciate the irony of those beliefs.
My child is adult enough that belief patterns I encourage are very unlikely to become deep patterns. That is, I’d have to work to indoctinate my son, and he’d actively resist if my indoctrination was outside of societal norms.
He didn’t grow up exposed to the social media I suspect children do now.
How does a parent inoculate a child to the influence of social media without also creating a mindset willing to believe in a nebulous “them” that controls things—a mindset, I believe, that makes a person more likely to be controlled?
There’s no magic bullet. Manipulation exists, and manipulation based on claims of manipulation exists.
I recommend you explain but don’t force your view of the world onto kids, and teach kids how to think well for themselves instead. So, just steer them towards things like history, social sciences and to a degree hard sciences and let them make sense of the world for themselves.