The second level is the primary character or characters. The character or characters' struggles reflect that theme, and they must work their way through the plot to find their own answer.
Other characters will reflect elements of the question in their interaction with the plot.
The third level is the plot itself. The plot must force the characters to find the answer to that question.
In essence what this boils down to is character equals plot, and plot equals character, and both answer the Big Question.
All of this sounds rather esoteric with the result being a morality play, but it isn't, really. What you are doing is creating a skeleton to build your story on that will give it depth.
The Big Question is one you ask yourself as you develop the story, but the reader may never be aware of it in a conscious way.
The really important thing to remember is that you must find a question and a story means of examining the two sides that interests you. You will be spending a lot of time with this story and its characters, and no book is more unpleasant to write or impossible to finish than one you are either bored with or has major characters you don't like.
We'll look at different places to find a Big Question in the coming blog articles.
Part 1: http://mbyerly.blogspot.com/2022/06/the-big-question.html