A classic trope in fantasy is the idea that magic despite it’s limitless potential is said to always come with a price. It is a fair exchange rule that both comic publishers DC and Marvel comics follow with fictional magical rule set for all it’s fantasy related characters to explain power levels of these characters.
An fun example would be Constantine being immediately sober in exchange for a powerful spell to defeat a parademon.
This concept has been explored in books like Hellraiser, Book of magic and Justice league dark.
However Shazam and those with the powers are largely removed by that restriction able to use their powers with very little restrictions to it’s use. The Shazam family and Black Adam are able to do incredible things like flight, strength, speed, with endurance, intelligence and longevity, without risk of losing something in a fair exchange if they say the word. The powers can’t even be taken away by the wizard so they’re only thing he’s able to do is banishment. The powers of Shazam hold very little downsides but if there are more rules I didn’t list please let me know below.