The reality of Donald Trump as President of The United States of America has spoiled (destroyed?) how authors create their dystopian villains. The writer's imagination, however nimble, can't hope to keep up with the variety and volume of Trump shenanigans.
So, after eliminating his scandals, his tweets, his slavering approbations given to dictators, the only plausible scenario for a writer of dystopian novels using a Trump-like character as the villainous tyrant is this:
Since, as I said, there are no other options for this type of character, and so some author must be arriving at this same conclusion, and I don't wish to tread on any toes, I'll refer to the dystopian leader as "President Turnip."
A billionaire runs on an anti-Turnip campaign, promising to seize President Turnip's assets and put him in prison. On the eve of the election, as Turnip realizes he will lose, he evades capture by disguising himself as a woman (and not a "10" as his looks are harshly criticized by witnesses). And frankly, everyone was glad to see him go.
But as he alienated every world leader with his attacks and insults, no country will have him. In the only move that makes sense to him, Turnip converts to Islam and joins ISIS in its fight against America.