And no, being elected to a public office is no blank cheque to dismantle checks on that office by other branches of government.
Does that mean that the real coup happened when Trump picked the supreme court justices? Perhaps, but again it was very legal, and not particularly out of step from previous norms.
If you compare that to germany in the 1930s, a common example of a self-coup, you'll see some similarities but also large differences...
> The Reichstag building... caught fire... Hitler immediately accused the Communists of being the perpetrators... Using this justification, Hitler persuaded Hindenburg to enact the Reichstag Fire Decree. The decree abolished most civil liberties, including the right to speak, assemble, protest, and due process... the Nazis declared a state of emergency and began a violent crackdown against their political enemies... Hitler submitted a proposal to the Reichstag that if passed would immediately grant all legislative powers to the cabinet... allow Hitler's government to act without regard to the constitution.
https://en.wikipedia.org/wiki/Enabling_Act_of_1933 (Edited for brevity)