Not really, actually. Stories tend to end with the main character being victorious - in most of the good ones, they enter the final battle/confrontation/denouement as the underdog.
The problem with a protagonist being the strongest character in the story is that you run into what I call the "Superman effect" - if they can curbstomp any villain, there is no narrative tension (after all, they're going to win without difficulty). So, you have to find a way to get around the fact that the hero is so strong in comparison to everybody else.
Conflict works best when the protagonist is facing a force of antagonism that is equal to, or preferably greater than, themselves. This forces them to grow and reveal their true selves as they come up against it and lose at the beginning, until they finally come up against it and win in the end. And, this means that a lot of the time, a good protagonist will end the story weaker than the antagonist they just defeated.
So, there are stories where the hero is the strongest at the end of the story, or throughout, but a lot of the time that's pretty far away from ideal storytelling.