I’ve tried this. They don’t listen; it just goes in one ear and out the other, and that’s assuming you’re on good terms with the person you’re talking to. Otherwise, they just get very angry that you’re attacking their worldview.
The long and short is that these people have been lied to virtually non-stop for the past 40 years, and the first step is depriving them of their disinformation stream. From there, it’s a slow process that could take years, and that process is reset if they go back to listening to lies on Fox News or on Facebook/Twitter.
When I was in college, I found a hand-bound report from the Department of the Treasury, written in 1939, about the financial situation in Nanking during the Japanese occupation. I was writing a report about the Rape of Nanking for a history class, and I stumbled upon it while searching the university library.
I was shocked that it wasn’t in their archives, and even more shocked that they let me check it out.