How to keep the player on the left side o the screen?

I’m making a third person game and I’m trying to keep the player on the left side of the screen even when the camera rotates.

as @highpockets write, you can attach camera as a child of the player, however if you need a animated, less rigid or “natural” following, I did a script about a month ago, is similar to a ton of scripts that are already on the net, so I dont think to is a great discovery:

public class SlowFollower : MonoBehaviour {
	public Transform Target; //target to follow
	public Vector3 PositionFollowing;//position of the camera relative to the target 
	Vector3 PosBuffer = Vector3.zero;
	Quaternion RotBuffer = Quaternion.identity;

	// if u are using physics to move the player, to evade camera jittering use LateUpdate but, if it dont work like with me, use FixedUpdate 
	void FixedUpdate () {
		if (Target) {
			//chek if target change position or rotation
			if (!((PosBuffer- Target.position).sqrMagnitude < .001f)
				&& Quaternion.Angle(RotBuffer, Target.rotation) < .05f) {

				SlowFollowing();
				PosBuffer = Target.position;
				RotBuffer = transform.rotation;
			}
		}
	}

	void SlowFollowing(){
		PosBuffer = Target.position + (transform.forward * PositionFollowing.y + 
			transform.right * PositionFollowing.x - 
			transform.up * PositionFollowing.z);
		//u can change this to make a fast or slow following, to change position use lerp, this tweak just work if divide with 2
		transform.position = (PosBuffer+transform.position)/2;
		transform.rotation = Quaternion.Lerp (transform.rotation, Target.rotation, .2f);
	}
}

Cinemachine is what you need.