For such a long flight (relatively speaking) check the aircraft type for them. If they are tech savvy and plane has power outlets, then download app for IFE. (and power bank if no outlets). If not, then pack a book and earplugs. Newbies are often amazed at how noisy a plane can be or how bored you will get with nothing to do even if everything is “new experience” and you have a companion to chat up.