If you use Word’s endlessly confusing paragraph/header options, Word will also automatically create an outline of sorts.
You can use Word’s relatively hidden outline tools to create an index of chapter headings, then use these headings to navigate the document. Never fear, Word actually has a very well-hidden feature that will make your novel, non-fiction, or memoir-writing life immeasurably easier. Unfortunately, navigating a gigantic document in Word can be an absolute bear. With Word I can keep saves safely in my own folders, confident that I can open the doc in a decade or two. In screenwriting, I’ve been burned by countless writing programs that use proprietary formats or depend on the cloud and an internet connection.
While many writers out there love Scrivener and other programs, I like to stick to the familiar confines of Microsoft Word.