I meet candidates who worry because one of their examiners is a new academic:
“What if they don’t know enough? What if they are really thorough? What if they do something wrong?”
Not unreasonable concerns, but to candidates who feel like this I’d say, “How do you think that examiner feels?”
Personally, I imagine first time examiners are nervous, maybe even a bit stressed. The viva is important. They have to read and understand, summarise and comment, question and steer the discussions. They have to examine!
A first time examiner will have training, they’ll have colleagues they can ask for help and their own viva to influence them, but this is the first time they’ve been asked to do it. Whether it’s an academic’s first time or fifty-first time being an examiner they always want it to go as well as it possibly can.
When I imagine how an examiner might feel and what they might do for the viva, what I imagine is very close to how I think candidates feel and what they do. They’re both talented, both might be a little nervous, generally, but because they want it to go well they’ll both be prepared.