Well, since it's impossible to really alter the collar, or to let out a shirt, the only real option (other than going for a different brand) would be to buy the 14.5 traditional fit then have it altered to make it less baggy.
You won't find it on their website, the 'Lauren' brand is not even owned by Ralph Lauren, it is licensed by Peerless, the same people who make low-end fashion brands like Michael Kors, Joseph Abboud and, here's the kicker, Donald J. Trump Signature Collection
There's also usually a piece of linen or silesia used to reinforce the button areas, and its possible he might be using a piece of fusible here rather than sewing it to the canvas. Tbh there's very little wrong with using fusible in a few select places, such as here and behind pocket openings, as long as the main structure of the coat is floating canvas.
Eh? If it were currently a 3-button that would make sense. But if it's a 2-button to start with then it already rolls to the second button, there's nothing about the roll that needs to be changed. The only difference I could think of would be that normally there would be some reinforcement piece attached to the canvas where the button and button-hole are to be placed, to strengthen the area, but missing this shouldn't be too much of a problem if the button is not going to...