Try that in a WWII tank on soft ground and you have a tank missing a tread.
Yes in low gear a tank should be able to turn a fairly tight " U " without causing problems.
But it wouldn't be that tight except in low gear.
The 2 levers your talking about are clutch's, that combined with individual track brakes means that you can almost lock the inside track. So yes you could reduce power to the inside track. At the same time apply brake to the inside track. However doing so adds a lot of side pressure to the inside track. Seriously putting it at risk of popping a track pin leaving you parked there till repair crew could get to you.