Do collapsibles work in PDF documents?

PDF is by its nature a more fixed format than a Word document, and so PDF readers don't support the kind of hiding and showing necessary for collapsibles to work. 

When creating a PDF file, you need to decide in advance which sections are hidden and which collapsed.

There is one advantage in this: if you have a long master document, but you want to create various fixed-length shorter versions in PDF, you can easily hide or show the relevant sections before generating a PDF file.