Are you denying that Trump and the MAGAts have already chipped away at our Constitution? That they've undermined American trust in our institutions?
The way it will work is for the majority of Americans to actively support or turn a blind eye to what they are doing. Rome and the Weimar Republic didn't collapse from without, they collapsed from within. Hence the quote from Star Wars: “So this is how liberty dies: with thunderous applause”.
FWIW, it wouldn't happen on Day One. It would evolve over the year and really begin when Trump declares martial law with the majority assent of Congress.