This is an impossible question to answer with certainty for pretty much everyone. Maybe the extremely suicidal or the terminally ill, but likely not anyone else.

Death (and our perceived relationship to it) changes with our proximity to it. So, being existentially and emotionally prepared for death when you’re young is very different from when you’re old, and from when death is pretty much imminent. I would wager even people who report a high degree of confidence that they are prepared for their eventual death are less so (and likely much less so) when they are facing imminent death. I imagine the number of people who don’t experience fear when their death is imminent is actually quite low.

I have considered myself prepared for death for much of my adult life, but since sometime in my 30’s I have also accepted that I can’t predict my preparedness in the months-to-moments before I die. The existential threat of your existence ending is simply too dependent on its immediacy to be predicted with certainty ahead of time.