You need to hear a few stories before a full picture of the viva comes into focus.
One bad story could convince you (wrongly) that you’re in for a bad time.
One good story wouldn’t explain enough of what to generally expect.
Listen to the stories of PhD graduates generally to get an overall sense of what happens. Ask two or three friends from your department about their vivas to begin to get a sense of the process, expectations and experiences that candidates have in the viva. Vivas are generally fine. They can be challenging but not negative, difficult but not something that needs to be endured.
A sample of one isn’t enough, but a few stories can help you feel good for the challenge ahead.