Ben Carson published an op ed on February 26 about the patriotism of "our brothers and sisters in the Territories of American Samoa, Guam, the U.S. Virgin Islands, the Commonwealth of Puerto Rico and the Commonwealth of the Northern Mariana Islands.” Trump used the same wording in an op ed he published on March 9. And that's only the beginning. The two columns share about half of their language. Clearly, without any room for doubt, the Trump column lifted specific wording and the general concept from Carson's column. You can see the two columns side by side here.
I'm sure neither Trump nor Carson penned their op eds. I don't know if either of them even bothered to look at what was published under their names. Someone in the campaigns probably decided it was a good idea to pen a column, and some staffer wrote it. Trump picked up Carson staffers when he left the race, so one of them might have done the cut-and-paste from what was already on the Carson hard drive, with a few variations.
Trump's not the first political or academic plagiarist, and he won't be the last. Still, when Joe Biden didn't bother to attribute part of a speech he gave to the original speaker awhile ago, it cost him big time. It might have even cost him a chance at the presidency. Rand Paul got caught copying stuff straight from Wikipedia and other online sources without attribution, but he never got far enough in his presidential bid for it to come back to haunt him. Authors get their hands slapped for this kind of thing and lose prestige and credence which they have to earn back, if they can.
Will the Trump campaign word theft matter? Of course not. Next to the stuff he's gotten away with so far, this is like taking an extra M&M out of a candy bowl without asking first. The guy is good enough, he might even work it into his speeches and get cheers for his efficiency. "Who has time to make sure every word I say is mine? How PC can you get? There's just not enough time. I'm too busy Making America Great Again. U.S.A. U.S.A. U.S.A." (The crowd goes wild.)