Clamp camera position:

Vector3 position =
    transform.position;

position.x =
    Mathf.Clamp(
        position.x,
        minX,
        maxX
    );

position.z =
    Mathf.Clamp(
        position.z,
        minZ,
        maxZ
    );

transform.position = position;

Clamp pitch:

pitch =
    Mathf.Clamp(
        pitch,
        -70f,
        80f
    );