When everything is working correctly, firmly pulling on the parking brake lever multiple times will adjust the rears. And if you make it a habit to use the parking brake every time the car is parked, the rear drums will never need adjusting. The parking brake will do it.
Before you install the rear wheels, adjust the rear drums shoes (pull the drum and turn the star wheel) such that you can barely fit the drum back over the shoes. The shoes will lightly drag when you turn the drums by hand if the brakes are set correctly.
If you don't do this, you may find that your brake pedal goes to the floor and no amount of bleeding will help. Drum brakes like to be set up tightly. As your new brake shoes wear in, they may require more adjustment either by parking brake operation, or manually.
My procedure is to have the wheel/tire installed and adjust the star wheel until you can no longer turn the wheel by hand. Then back off the star wheel a few clicks until you feel a light drag from the brakes as you spin the wheel. This works well if you don't have the auto adjusters, or if they are not working (I've never really been able to tell if mine are working).