The developer for Spectrum Break has open sourced their 2D camera tracking plugin for Unity. Called Game-Eye-2D, the plugin is a "component based orthographic camera extension for unity that tracks 2D environments."
From the description:
A component based orthographic camera extension for unity that tracks 2D environments. Included are scripts that help you track 2D environments. When setup, the camera will follow objects in your scene, or zoom to fit them all, or use input from the player to track the scene, etc...
A full tutorial is available on YouTube:
Learn more and get the code at the GitHub page: https://github.com/JasonHein/Game-Eye-2D.