He pretty much did, in the areas the Germans actually took over an occupied. The Einsatzgruppen were especially brutal in their actions against the Russians. And, of course, of the millions of Red Army troops who were captured by the Germans, only a very small percentage survived the war.
My point being is that Hitler should have employed a “divide and conquer” approach, I think it would have been very easy to convince a lot of Russians to turn against Stalin and refuse the fight for him.
Win wars by making it easy for the enemy to surrender.