I'm not going to comment on the Pilot side of this as there are many more more qualified than myself to do so.
On the WSOp side of leadership, it's another one of those "depends where you go" type answers I'm afraid.
On the ALM-FW side, there is an awful lot of the teamwork aspect, but there is also a fair amount of working on your own initiative. As a loadie you will have to direct all sorts of people in your efforts to complete the task, from movers to passengers, with stewards thrown in on the "shiney" fleet.
As for the "traditional" leadership aspects, you probably won't get involved too heavily until you become an experienced Sgt or FS unless you involve it as part of a secondary duty.
(As always, I stand by to be corrected
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