The French verb tutoyer has no real English counterpart. It is used to indicate the use of the familiar form of “you” — the second person singular, for which English also has had no parallel since “thee” fell out of common usage around 1800. The nearest equivalent verb might be to “first name” someone; it’s an awkward locution but we know what it means.
Trump, it turns out, knows — or, rather, intuits — exactly what tutoyer means. I doubt he could tell me what I mean when I say to him, Ne me tutoie pas, s’il te plaît, nor would he recognize the inherent disrespect. But it’s a technique he uses daily: Deborah Birx, whatever her flaws, is a medical doctor who has earned her degree and the respect that goes with it. To anyone not bred in a stable she is Dr. Birx just as Anthony Fauci is Dr. Fauci. To Trump they are Debbie and Tony, and not because he’s particularly familiar with them, nor because he socializes with them, nor because he wants to run a more informal White House.
No, it’s a power play: he first-names them to demonstrate the inherent disparity between their positions. They are mere public health officials, civil servants; he is the President of the United States and will be addressed as such. It’s a sign of contempt — everything, with Trump, is a sign of contempt, except for his fawning over dictators. There, too, he recognizes the disparity of power: theirs is absolute, his is a gift from a servile senate majority. And as such, it is time-limited.
Got that, Donnie?
Common Cents 
Donnie it is, from here on out.
If I could have come up with a more humiliating diminutive, I would have used it!