This is a great article:
https://apnews.com/article/trump-rhetoric-lies-bully-pulpit-federal-indictment-bb5c99ee151d19085772f8e7c3183fd4
“Scholars like me who study presidential rhetoric, presidential communication, they call it essentially a second Constitution,” said Jennifer Mercieca, a communications scholar at Texas A&M University. Having presidents communicate directly to the public “changed the complete balance and separation of powers without having a new constitutional convention. It made the president the center of our political system.”
Trump, in effect, is arguing that his words as president carried no special force and he was simply exercising his free speech rights.
“Most presidents have a sense of the importance of language — of the written word, of the spoken word,” said Wayne Fields, a professor at Washington University in St. Louis and an expert on presidential rhetoric. “Some of them are not particularly good at it themselves, but they rarely are quite so dismissive of it as Trump has been.”