@momasaurus, I was looking at the H RTW this summer. There were patterns inset into, say, the front of a shift or top. They were probably printed on, actually. But it's possible to inset a square into a garment front in a "reverse applique" technique. I just think it would have to be interfaced to have a "hand" comparable with the rest of the garment. A good tailor could probably do it.
There is a dress or top style that I see as a coming style: flared sleeves. 70s-influenced. I made a blouse with flared, pointed sleeves and lined the them with the patterned silk I used for the skirt. There are sewing patterns for flared sleeves with lower arm slits which expose a contrast lining even more.