There is no template as far as I know. But if you are familiar with Unity it should be real easy to convert 3D tutorial info for 2D game. There is this guide on key differences between 2d/3d http://orkframework.com/tutorial/howto/2d-games/
If you don't have your own 2D art, depending on what type of 2D game you are looking to make you might find art on https://opengameart.org/ or asset store.
If you don't have your own 2D art, depending on what type of 2D game you are looking to make you might find art on https://opengameart.org/ or asset store.
https://unity3d.com/learn/tutorials
If you scroll down a bit, you'll see tutorials by topic. It's good to go over all of them, but the key ones for you are:
https://unity3d.com/learn/tutorials/topics/interface-essentials
https://unity3d.com/learn/tutorials/s/2d-game-creation
https://unity3d.com/learn/tutorials/s/animation
Once you familiarize yourself with basics, try one of the game tutorials like:
https://unity3d.com/learn/tutorials/s/2d-game-kit
When you acquired all the skills tutorials will teach, you should feel confident in modifying ORK tutorial to 2D gameplay.