You don’t get to choose your examiners, officially, but you can have a conversation with your supervisors about who might be a great examiner for your viva. Make sure you do that.
You don’t get to veto potential examiners either, but you could raise your concerns and expect your supervisors to listen. Don’t simply say yes if there’s someone you really don’t want; dig into why you are concerned and see how the conversation goes.
You don’t get to choose or veto your examiners, but you can choose to lead the conversation. Be pro-active: think about what you are looking for, who might be great, and start the discussion with your supervisors.