You can check it out by jumping to 10:40 of this video.
It shows that batman's cape can be stretched like a wing, when he landed on the ground the cape behaves like a cape.
I think this may be done by adjusting the skin radius, small radius will make the cape looks like a wing, big radius will make the cape softer and looks like a cape.
but this radius is baked into blueprint, I didn't find a way to change it on the fly.
Any help would be greatly appreciated, Thanks