Yes! Once you open the itinerary in either app, you have the option to toggle offline mode at the top. It should look like this:
Once you select the toggle this will download the itinerary for you and will look like this:
Please note that not all images and maps may download instantly. So it's best practice to tap into each day and view all attachments, places, etc. while online because the app will download and save this information that you view so that you can view it again offline.