Yes, absolutely. They are called elevons and can be found on many delta designs.
Elevons can function oppositely as ailerons, or together as an elevator.
The benefit is that, at very high speeds, having them closer to the fuselage on a strong structure reduces torque stress on the wings, which can warp if the aileron force is too great.
If one wished to lower the vertical stabilizers to a horizontal position, this would result in a loss of directional stability on the yaw axis.
Raising or lowering an aft horizontal surface to vertical, as with the XB-70, can have beneficial effects by increasing yaw stability, and increasing lift coefficient at supersonic speeds when lowered.
Raising the canards would result in a loss of yaw stability. It may be better to bring them completely in line with the wings at higher speeds, as wing strakes, and to raise them up at lower speeds/higher Angle of Attack as stall inhibiting canards.