Historically that’s not necessarily the case. Authoritarians who come to power via somewhat democratic means in their first terms to be much more mild relative to subsequent terms where they solidify their hold on institutions.

One notable example would be Putin’s first term (which is largely seen to be a fair win) or even when Medvedev was ordered to warm the seat. It always only gets worse, at least from historical examples.

The bigger question is whether the US opposition has any willingness to fight, which I don’t believe to be the case.