I don't think Nietzsche says much that's systematic about the Overman. The creative ruler is supposed to be beyond slave morality (good and evil), but not beyond good and bad, the values that express his nature without apology.
The lower ranks get caught up in the ruler's creative schemes and resent the amoral, discriminatory triumphs of will. It's not that the Overman wants to conquer the masses, since that would be almost like a person wanting to crush ants. But the Overman can't help doing so just by expressing his noble, beastly nature. This strikes me as mainly a rationalization of social Darwinism.
The Overman has no use for Christianity because that religion is opposed to nature. The Overman's religion celebrates nature's amoral, often destructive creativity. The Overman creates new worlds and it's the masses' task to live in them, much as that Bush advisor said about the "reality-based community" (link below).
Like a Christian slave moralist, Trump tried to bullshit his way out of inhuman reality, and his lies didn't rise to the level of myth. Trump isn't in touch with the natural facts, as in his narcissism and sociopathy, so he's no Overman.
