If styles only assist in making things look pretty they wouldn't be supergirl-in-disguise-worthy. Add functionality to styles and now we're talking. Remember the days of typing out your table of contents only to have more edits come in. The edits change the pages and the table of contents you carefully typed is useless. Those days are over. Let's go back to your 32 chapter book. Because you used "Chapter titles" for every chapter tile in the book you don't have to retype anything. Instead you will insert a dynamic table of contents based on your style. The table can be updated to reflect edits to your document without retyping or counting pages. [In Word Help keyword search "Table of Contents" to learn more.]
Using styles can seem complex at first. Don't give up, supergirl, they're worth learning. Begin with the built-in styles in Word. Apply them, modify them, see just how many different options you have. When you're getting the hang of things look for an online tutorial to teach you more. Let's see where sensible styles take you.