This could be either an exciting finish that beat expectations, or an amazing plot twist. And ending doesn’t need to be a final scene, but it should be somewhere near the end of the movie.
Off the top of my head:
Jaws - shark explosion
Star Wars - the entirety of the Death Star assault
Rogue One - Vader’s light saber battle
Memento - plot reveal
Avengers End Game - the funeral
The God Father - The baptism
Sixth Sense - reveal of Bruce Willis’ character
Usual Suspects - exposition of the elements of Verbal’s story
Killing Fields - Schanberg and Pran reunite
Big Wednesday - the arrival of the titular swell
Sicario - Benicio del Toro taking care of personal business
Point of order, but the Christening scene wasn’t the end of the Godfather. Nevertheless, the actual ending (office scene, Clemenza kissing the ring, Al closing the door as Kay looked on) was pretty damn good.
I don’t know as if I’d call it good or what-not, but the ending that stuck with me the most - because it came out of left field - was ‘Dirty Mary, Crazy Larry.’