He'll change, but it will be a natural change and it won't be sudden. In hindsight, looking back a few months, it will be a remarkable change in presentation.
Trump's public/rally presentation is a self-created caricature. He will slowly drop that, and the public will start to see more of how he deals with issues and conflict when he is in charge. The caricature is to get people to put him in charge. Before the election, he will be acting as if he is in charge.
Trump needs to watch a bunch of Reagan videos to learn the Reagan charm.