I’m not saying I have a better idea, but the problem is: trying to present facts to people who act as though facts are no better than opinions; you point out that Trump has made a bungled mess of XYZ; they show you a tweet where Trump claims that not only was his handling of XYZ the best that anyone ever did, but that everyone else saw how he handled XYZ and agreed he was the best they ever saw.
Moreover, any reliable source which might be presented as a rebuttal to Trump’s claims are immediately suspect. They would be called out as fake news, deep state actors, and/or political hack jobs. Nothing, and I mean literally nothing that can be presented to a dyed-in-the-wool Trump supporter will convince them; their minds will not be swayed.
If nothing else, every Trump admin official should be identified with the kicker “former Trump administration official” in every mention by the media or in social media for the next two decades. Never forget. Never let them even hope that we’ll forget.