We have created a Main Camera by simply adding a new camera Game Object to the scene, then tagging this GameObject with the preset tag of Main Camera. It is important that the Main Camera of the scene is tagged with this special predefined tag.
Some scripts explicitly search for the Main Camera of a scene using the Camera.main C# expression. So, we should always have the Main Camera in scenes using such scripts.
You can learn more about this in the Unity manual at https://docs.unity3d.com/ScriptReference/Camera-main.html.
By changing the Position and Rotation of this camera, we positioned it so that the player can see most of the main room where the ThirdPersonController character starts off. This fixed Main Camera might be sufficient if all the action for a scene is inside a single room. However, by making the camera's Field of View larger, more of the scene can be seen in the camera's rendering to the Game...