Resolution in 2d mobile game (full width, scale verticaly)

We are creating a simple 2d game designed for mobiles.

Our whole game is built using 2d sprites. The level is a horizontal "pipe" that is designed to fit the width of the device. Therefore, we would like to set our games width to fill up the entire screen of the phone and change how much we see above and below the character depending on the resolution.

Do you have any ideas of how we should go about doing that? I would gesss Unity has some built in feature for this or should I write a script that zooms the camera in depending on screen width?