All great bunker players do two things: They control where the clubhead enters the sand, and they create a lot of swing speed. You can see here Sergio has choked up a couple of inches on the grip. This makes it easier to hinge the club up on the backswing and up again after impact. That hinging and unhinging generates clubhead speed through the sand. Also notice how he turns his body through to face the target. A full turn allows him to accelerate the club into the follow-through. If he stopped rotating, the club might get stuck in the sand.
The other trait of top bunker players is controlling the club’s entry point into the sand. It is a function of posture and weight location. Sergio’s weight is on his front foot. It’s a good idea to set the weight on the front side at address and keep it there throughout the swing. As long as the ball position is forward in the stance, the clubhead will touch down two to three inches behind the ball, slide under it, and push it out.
Also see how Sergio has maintained the forward tilt of his upper body. He hasn’t stood up to watch the shot. A good swing thought is, Splash the sand onto the green. The ball will pop out with it.