Doctor Important or Professor Amazing perhaps, but your viva examiners are still just people.
They know that exams can be stressful for the people taking them.
They know that you have worked hard. They know you might be nervous.
They can’t take your nerves away but they can create as good a space as possible for the viva.
Your examiners will do everything they can to make sure the viva is fair. Remember, they’ve likely had a viva or similar in the past too. They know what this means to you.