Any genre or era... what movies have opening scenes that effectively and immediately convey their themes?
Here’s one: Dumb and Dumber.
In the opening scene Jim Carrey tries and fails to pick up a girl at a bus stop. He’s the Limo driver but pretends to be the successful passenger. He mistakes Austria for Australia and makes terrible cliche jokes and gets his head stuck in the car window.
We get the movie’s themes: the character is looking for love (or, at least, a woman), he is a fucking idiot, he will use deception in his quest.
We know right away the movie is a comedy. And there’s a hint at the road trip structure that will follow. This is a precision-tooled film.
Here’s another: The Matrix. But it’s more the opener is more a sequence than a scene, from noir to bullet-time.
The Coen Brothers have good beginnings... maybe O, Brother...