The Rule of 3 Colors is more of a guideline, than an unbreakable law, as all rules, they can be broken. The rule of 3 colors is simple: pick one primary color. Then, pick two other complementary colors.
One super important thing to keep in mind: make sure you don’t select three important or strong colors together. In a way, it should be one primary color as a hero, and the rest should be secondary, as a sidekick to the hero. Here’s why the best movies use three predominant colors.
As Mies van der Rohe, the uber famous german architect, used to say: less is more.