At the end of your PhD, you could say, “I don’t know how to run that type of an experiment,” or “I don’t know about that topic,” or “I never read that paper,” and feel bad…
…or you could choose to list all of the things you can do and know.
Sometimes listing what you don’t do or don’t know can be a way of finding your edges; for the viva, it’s better to look inside those boundaries first. Get a real sense of your mastery. What skills do you have? What knowledge have you learned? What ideas can you share?
Explore what you don’t do if you must. Lead with what you can do.