I do not know if that is an S-duct; the position of the exit looks to be on the chassis, which I think is illegal. The S-duct has always been right between the chassis and the front crash structure/nose cone, which is a loophole in the rules.
It could be experimental for next year. It could also just be aero test devices. This is how your typical S-duct looks when the nose cone is removed:
However, I could also be wrong about this. Force India has a similar set up as Mercedes:

I think the vanity panel is used here.