Код
var limits = new Vector3(10, 3, 1);
var pos = target.transform.position;
var min = pos - limits;
var max = pos + limits;
camera.transform.position = new Vector3(Mathf.Clamp(camera.transform.position.x, min.x, max.x), Mathf.Clamp(camera.transform.position.y, min.y, max.y), Mathf.Clamp(camera.transform.position.z, min.z, max.z));
не тестил
