I believe you have answered my question, thanks!

Ah, I was referring to Ogryn being put in charge of other Ogryn, as a squad or as a detachment to another IG force. Not neccesarily an Ogryn sergeant in charge of humans, that would never happen. I was inquiring into the fact that they have been given greater authority over their own kind

I'd like to point out this parcel of text, taken from the lexicanum page. That does not directly limit them to Only War. "The unit consists of squads, each led by an Ogryn Sergeant who has received BONE treatment, allowing them to communicate orders to their squad." wh40k.lexicanum.com/wiki/Ogryn#Imperial_Guard