It's hard to say for sure. If the author or creator has stated that it's based on real-life, then it might be. But often, stories like these can be a blend of reality and imagination to make it more engaging.
Mafia Inc is typically not a true story. It's more of a fictional creation that incorporates common themes and tropes associated with the mafia world to engage and captivate the audience.
Monsters Inc. is set in a world where monsters generate energy from children's screams. But as the story progresses, we discover that laughter can generate even more powerful energy, leading to a major shift in the monsters' way of doing things.