Counter factual questions can be a tricky thing to deal with, especially when it focuses on something like the Holocaust. A lot of how you see the question will depend on which side of a certain historiographical debate you take. The debate in question is the functionalism vs. intentionalism argument. To give a brief overview, functionalists believe that the Holocaust as we understand it was the culmination of a number of structural, political, and economic factors whose enactment bordered on improvisation; ideological conviction less of a central role, and other factors such as the invasion of the Soviet Union were more important. Intentionalist historians argue that Hitler and the Third Reich's ideology was central for understanding their actions in World War 2, and the war (as well as the domestic policies that were necessary preconditions for what would become the Holocaust) was a natural outgrowth of those policies. To oversimplify it a bit: "World War 2 was a necessary factor for the Holocaust" (functionalist) vs. "the Holocaust was a necessary factor for World War 2" (intentionalism) (u/commiespaceinvader please correct me if I'm off base here)

The functionalist's answer to your question would be that without World War 2, the scope or execution of the Holocaust would have been considerably different. In other words, the invasion of Poland and later the Soviet Union were necessary factors for enacting the Final Solution. Functionalists will (I think with good reason) point to the vacillating policies of the Third Reich in the 1930s as proof that full-blown war was a necessary factor for the Third Reich to take their racial supremacy policies to the absolute extreme. In other words, we shouldn't expect the Third Reich to wait until after the war was over because that assumes a far greater level of long-term thinking than actually existed.

The intentionalist would most likely argue that there would be no invasion of Poland or the Soviet Union without the underlying ideological drive to commit genocide on the Jewish, Romani, Slavic, and other populations that the Third Reich deemed as inferior. As such, the enactment of the Holocaust had to go hand in hand with the war because it was the primary ideological and political reason for fighting the war in the first place.

The other problem with the question (and I'm not criticizing you for asking; these kinds of things are important to think about even if there isn't a clear answer) is whether or not the Holocaust had a discernible impact on the outcome of the war. Could the Third Reich have defeated the Soviet Union using the resources it allocated for the Holocaust? Historians such as Yaron Pasher have argued that yes, it did have an impact. Others have argued that the supplies of oil, manpower, and metals was such that there was simply no way to defeat the Soviet Union (and this question leads into another debate about the balancing of Moscow and the Caucus oil fields in German military planning. I think you can see a pattern emerging...)

The short answer is that historians have not yet reached consensus on what the dynamic between World War 2 and the Holocaust was.

Sources:

Bergen, Doris. War and Genocide: A Concise History of the Holocaust. 2001

Goda, Norman. The Holocaust:Europe, The World, And the Jews: 1919-1945. 2012

Pasher, Yaron. Holocaust vs. Wehrmacht:How Hitler's "Final Solution" Undermined the German War Effort. 2014