Shorts and Sleeves
Wearing a white button up tucked into denim isn't new. This is not me being a trend setter, and I'm not "discovering" anything unusual here. It's a classic. It's something that can be repeated over and over, and it will never go out of style.
Next time you wear an oversized white button up, try pulling it back to where the shirt's collar passes your collar bones and then unbutton a few front buttons. It's going to hang much looser at the top and the shirt will naturally run off your shoulder. Again, this isn't anything new, just a styling trick to make something classic a little more "yours" if you will.