Your PhD success is hundreds of days of work – thousands and thousands of hours of learning, doing, achieving, growing, making, failing(!) and persisting. Your PhD is not defined by a few hours of discussion with two examiners. You need your viva to go well, but you need all of the work that comes before to get you there.
Your earlier success, all those years, helps you through the viva too.
It’s not just one day that determines everything. It’s one day when you get to demonstrate who you are, what you’ve done and what you can do.