Whatever challenges you faced during your PhD, they helped you get to submission and to the viva.
Whatever prep you do it will build on a solid foundation of knowledge and ability that you have developed.
Whatever disruption you encountered because of the pandemic you have worked around and persevered.
Whatever questions you are asked you will be able to find a way to respond.
Whatever you feel before your viva, you are a talented and capable researcher.
Whatever happens you are good enough.