Hi there, what you're asking about may fall under what is called the "intentionalism vs. functionalism" debate in the historiography of the Holocaust: that is, whether the Holocaust was intentionally planned from the top of the Nazi regime down, or whether it just sort of happened in a climate that was permeated by anti-Semitism and encouraged bureaucratic infighting. These previous posts may help shed some light on the question:
https://www.reddit.com/r/AskHistorians/comments/2gkamb/how_was_the_holocaust_organized/