Expectations for a viva fall within ranges.
There are common lengths, probable questions and likely areas of interest. It’s not as simple as rattling off a bullet point list of what will happen. There are ranges of aspects to consider and knowing about them helps. Generally, it’s clear to see what’s involved with a viva.
It also helps to remember what is definite about your viva.
You did the work. You wrote your thesis. You developed and became a better researcher. You know who your examiners are. You can prepare for your viva.
There are ranges of expectations for a viva but a lot you can know for sure about yours. Explore and remember all you can about both areas as you get ready to meet your examiners.