You have actually asked two questions:
First is: how to add binding offset to the document?
You can use the geometry package and specify a bindingoffset. The package documentation has a quick summary of all the lengths required.
Second is: do I need to specify a binding offset?
This is best answered by the FAQ from the printer of your book. For example, Amazon's KDP provides minimum inner margin depends on the length of the book. A rule found elsewhere on this website suggests reserving
0.5 * thickness of the book
as the binding offset. The thickness of course would depend on the number of pages and the type of paper used.
Since you specifically asked about the default values from the book class: you can find out the default values by using the layout package as in this Q+A. Compare that to the amount you need as suggested by the printer.