I once got on the topic of the moon lending with a creationist co-worker. He said he wasn't sure, but that if it happened we should be able to see it from satellite pictures. So I said "yeah you can", pulled it up, and zoomed in on a landing site. You couldn't see footprints or anything, but you could see the shadow of the flag next to clearly man-made debris

I showed him exactly what he agreed would be proof in a difficult to fake form, and it just temporarily nudged the needle for him

Now, I fight conspiracies with the opposite conspiracies.

Earth is a 4D hypersphere, the earth isn't hollow, Agatha is just another part of the surface reached by holes

The elites are hiding all the best vaccines, like the ones that cure cancer

This was highly effective when I used it in real life.

The conspiracy theorist got real mad demanding I name sources, I kept telling him to find it on the internet with fake search terms.