The fascist project - as far as what at the time could have been understood as an external racial group (Slavs, Africans, etc.), which is not to say that is was taken as such by default (the definition and identification of races was a controversial issue, as was the correspondance between biological and cultural terms) - focused mostly in the establishing of a form of political hegemony driven by "cultural superiority". This was a traditional theme developed within the Italian nationalist ideological formulation around the matter of the relations between Italian and Slavs in the Balkans (where the nationalists argumented in favor of the traditional political priority of the Italian urban minorities over the rural majorities) - simply put, the idea that inferior cultures were necessarily and (perhaps) in their own interest subordinated to superior ones. It was then for the inferior culture to adapt to such process of subordination - in a pattern of assimilation that was frequently compared to that of the Roman Empire. As did Mussolini himself in his private speech of October 1938

The racial problem is for me one most important conquest and most important is its introduction into the history of Italy. The ancient Romans were unbelievably racist. The great struggle of the Roman Republic was indeed to know whether the Roman race could aggregate with the other races.

There was therefore no particular accent on the physical extermination of those different groups - since there was, at the root of it, no reason to question the possibility of this "cultural assimilation" process. Those who challenged this view, and suggested a negative answer, were in the Italian context a small minority - and mostly not influential as well as quite disliked.

Notably, the practical means of this assimilation could very well include violent and deliberate actions; consider for instance the systematic killing of livestock (not only the main source of wealth but the only mean of sustenance for large portions of the interior population) during the "pacification" of Libya, which Rodolfo Graziani himself commented in his memoirs observing that “nothing new can be built, unless one destroys […] a past that is no longer keeping up with the present”.

Unfortunately, I do not have enough time right now to cover the evolution of this approach during the 1930s. But I have written here something that should more or less discuss the same points I consider relevant for your question.