Create an action-oriented and evocative metaphor for the most basic/central theme of the story.
Star Wars: A long time ago in a galaxy far, far away...
Alien: In space, no one can hear you scream
Ferris Bueller's Day Off: One man's struggle to take it easy.
Jaws: You'll never go in the water again.
Platoon: The first casualty of war is innocence.
The Good the Bad and the Ugly: For three men the civil war wasn't hell. It was practice.
Bonnie and Clyde: They're young, they're in love, and they kill people.
Treasure of the Sierra Madre: The nearer they get to the treasure the farther they get from the law.
Grosse Pointe Blank: Even a hitman deserves a second shot.
Mars Attacks!: Nice Planet. We'll take it
https://www.studiobinder.com/blog/best-movie-taglines/