It might be a surprise to know exactly what your examiners think of your work, but it doesn’t have to be a surprise to know what other people more generally think of it. Share your work, get feedback and keep building on what you’ve done.
There may be a surprising question you’ve not considered before, but your general talent at answering questions shouldn’t be a surprise to you. Find opportunities to receive and respond to unexpected questions.
You might be surprised by a particular correction that you get, but you should know that most people are asked to complete some level of corrections. After the viva you’ll be given an opportunity to make your thesis even better.
There could be surprises in the viva, but there’s a lot that you can do to meet any challenges that come up.
Do the work, prepare well and the surprises won’t matter so much.