If you think of authoritarianism as more of a "spread" and not as a black-or-white thing, you can see where the problems with "Trumpism" are.

Using the terms of The Economist's "democracy index", I see the United States under Trump 2.0 as a denigrated "flawed democracy". There is even some danger of the United States backsliding towards a "hybrid regime". Hybrid regimes combine some aspects of electoral democracy with some aspects of authoritarianism. Prominent examples of hybrid regimes include Turkey and El Salvador.

Maybe we won't get that far -- strong federalism will help here. But while The Economist has ranked the United States as a borderline "flawed democracy" for the last several years, I suspect 2025's rankings will be considerably lower. My "gut feel" is that the United States could end up ranked close to present-day Hungary, or Poland under PiS. In both cases from what I remember, democracy still was present, but considerable damage was done via institutional attacks on the press and the universities. A US attorney general arresting judges for what seems like a minor dispute (but one involving migrants) seems like a pretty big flag that some degree of authoritarianism has taken hold. As is the erosion of due process involving immigrants.

Long run, I think this institutional damage being done by Trump is the most concerning aspect of Trump 2.0. Trump is actively damaging future engines of American growth (research science and universities). My guess, too, is that the anti-immigrant hostility might damage the previous paradigm where many of the brightest in the world came to America for both research and careers. There is a significant core of American voters that supports this stuff; the most vocal of this core in fact cheer on the arrest of judges and actively attack technologies where the conspiracies overwhelm the facts. (Witness the recent push of a few states to actually restrict mRNA vaccines for... reasons? Nothing solid that I can think of.) I do not think that this element will go away after Trump moves on.