One of the beauties of writing is that there's no one way to approach plot. Each writer after a lot of trial and error finds the way that works best for them. One person goes after characters. One sees events. One knows the end before writing the beginning. One must get the beginning down before they can move forward. Some people write in drafts. Some people revise as they move forward. Each writer discovers what works best for them.
Just how many plots are there. Some people say a hundred or more, others think there might be two or three. If we go back to the very basics and look at the Greeks we see tragedy and comedy. This can be also seen as action and mental. No matter which way you tend to identify what a plot entails every story needs one. Because a plot is a road map leading characters from the beginning to the end.
Plots either depend on action which is a story that depends on doing something. On the other hand the plot may depend on the inner workings of the minds of the characters.
In an action plot the writer is attempting to solve a puzzle. How does the detective find the killer? How does the hero get the girl? How does the young wizard defeat the evil one? One can find this kind of plot in most genres.
Now the mental plot differs in what happens is the characters are searching for meaning. There can be action but the mental aspects outweigh the action.
So when you fnally decide to write a story, the decision becomes is this story to be plot driven or character driven? In plot driven stories the characters are there to move the action forward. The goal is the object. This doesn't mean there aren't internal struggles for one or more of the characters. It means the doing is more important than the being.
Character driven stories are more about the people and what they're doing, feeling and thinking. The action or plot part of the story isn't stage center. More the writer sends the characters on a journey of discovery to learn something about life.