Watch two documentaries on the same topic. Where they disagree is where you start thinking for yourself.

Any single account feels complete while you are inside it, because it chose what to include and left out the parts that complicate it. Two accounts expose the seams. The place where they contradict each other is where something is genuinely uncertain or where somebody has an angle, and noticing that is the beginning of judgement rather than absorption.

Pick a topic you care about and watch or read two takes on it from different sources. Write down the three points where they differ. Then look up one of those disagreements properly and decide what you think, with reasons you could say out loud.