In the first shazam, Billy Batson broke a staff to share his powers with his siblings. Breaking the staff led to the freedom of the gods, the Daughters of Atlas. In the second movie, Billy and his siblings had to face off against the Daughters of Atlas and save the world.
Two very important aspects happened at the end. The first fundamental scene that happened was Wonder Woman made an appearance. She appeared because she was the only God left at the end, and she had to help Billy.
The Second fundamental scene is the post-credit scene. In the scene, Billy was asked if he wanted to join the Justice League society. This is essential because it helps give a sense as to what may come to the future of the DC universe movies.
