I think it depends on the cover. I had an American Tonneau tri-fold soft cover off of the same vehicle your asking about. It fit and performed just fine on my 2019. I'm sure the average person couldn't tell it might have been from a different vehicle, however I could. It was just a little bigger than than it should have been. I used it for 6 months or so until I found an open box deal on a roll up cover made for the 2019.
It was just a little wide at the cab, it hung over the front corners maybe a half inch or so. I think it was more about the shape of the corners of the bed at the cab than the width if the bed. Never had any water in the bed with it.How big was it compared to the 2019 bed?