No.
And if they really used that adapter, it's never going to be any faster. They'd have to use the lightning to usb-c cable (which still won't make a difference with how current iPhone electronics are implemented).
The 6s will benefit from up to a 12w charger by using the extra headroom to power the device if it's in use while charging. If the phone is idle with screen off, charge times will be the same between the 5w and 10-12w chargers. The + models can take some of that extra power and apply it directly to the battery. Lots of threads here about it.