The verb translated as came out
could better be translated as went out
(as other translations have it). That awakens in our minds the picture of this horse and rider leaving the heavenly stage to accomplish its mandate. This point is significant because this first horse is the only horse of which we are told that it went
(= left the heavenly stage to fulfill its task).
2 And I looked, and behold, a white horse! And its rider had a bow, and a crown was given to him, and he came out conquering, and to conquer.