That isn't how armed forces tend to work, and it certainly wasn't during the Second World War. Where you got sent depended on your service branch, and which unit you were assigned to upon completion of your training.

To give an example, if you were in the Marine Corps during the war, it was almost certain that you would be sent to the Pacific Theatre, as an airborne infantrymen, Europe was far more likely.

As with now, you are sent to whichever unit needs men, in whichever theatre men are required. As such there is, and was, little room for choice.