Oh, definitely. Most of them are so thoroughly brainwashed by a steady, decades-long diet of objectively, factually incorrect garbage spewed by the Fox infotainment channel (I refuse to call it "news"), it would take professional deprogramming to break them out.
Every time reality intrudes on their fantasies - Hillary doesn't get indicted, COVID-19 doesn't vanish in the spring, the "storm" doesn't manifest, JFK doesn't come back from the dead, Trump actually leaves the White House, etc. - it leaves them in a state of shock, followed by the irresistible urge to double down even harder.
You don't bring people back from that, at least not en masse. You just consistently, continuously beat them during elections, depriving them of their ability to force their bizarre worldviews on others.
And, bluntly, you wait for them to die off. They catch COVID-19 at high rates, most of them are boomers, and because they're dying faster than the national average, the Republican party is actually shrinking. The oldest boomers are approaching 80, and it won't be long before we start seeing some serious demographic shifts because of that.