rejection of political plurality,

Like when so much money is funnelled into US politics that only two capitalist 'parties' are able to compete, and they have almost identical policies except for some window dressing?

the use of strong central power to preserve the political status quo,

Like when the republicans block democrat legislation, even though the democrats are in power?

and reductions in the rule of law,

What happened to Roe v Wade and how?

separation of powers,

Like when the previous POTUS secures a GOP majority on the Supreme Court, which the current POTUS can't change?

and democratic voting.

Like suppressing votes by criminalising being black and requiring voter ID?

The problem with the term 'authoritarian' is that it's either meaningless and applies to everybody or nobody and is used as a weak rhetorical device, or it's given some theoretical basis and it applies to every state and is used to shed light on state relations. Either way, it's not a coherent criticism in an of itself.