Your viva is a unique exam, tailored just for you and your thesis. No-one else will have this one-of-a-kind experience.
But like made to measure clothes, there are patterns. There are ways that things are done. Jacket sleeves stop at a certain point so the jacket fits well. A skirt would be no good if it wasn’t stitched properly. Vivas are unique for the individual candidate, but there are expectations for what they should be like.
Find out about regulations and expectations for the viva, so that when yours comes around you can be sure it fits you well.