An old trick for critical thinking (and from debate) which I think continues to be useful today, and one that I think has great utility in introspecting one’s own intellectual honesty:
Whatever position you are about to take in an argument, setup its opposite, and try to argue it through in your head. The harder this is, the more likely a) you are out of your depth and need to learn more or b) you have some deep-seated bias preventing you from arguing effectively…and that same bias is almost always blinding you to glaring holes in your own position.
I don’t think cognitive dissonance is as helpful as you make it seem, both because none of us are actually very good at it, and because (this may be unpopular these days!) I think it is possible and useful to “know” that things are true. The key to intellectual honesty is to reflect on your own starting points, so that you know the difference between a solid foothold and a shaky one. I.e. it’s more about keeping your ego in check rather than fighting against the biases that your ego leads to.