AskHistorians

Turn large swathes of Eastern Europe into Slav-free areas in which German farmer-soldiers would live in little totalitarian communes dedicated to Nazi ideology. There was a strong agrarian element in Nazi ideology to the better-known militarism.

Expand the Lebensborn program - encouraging people with perceived Aryan traits to breed, kidnapping children that met their criteria then getting them adopted by German families and other eugenics programs but on a much larger scale.