By starting with yourself.
There is nothing as powerful as a leader that does their own work. It is the most necessary ingredient of powerful leadership.
Note that this isn't the only thing you can do.
There are millions of ways you can develop leaders. Hire them a coach. Send them to experiential workshops. Have them take on impossible goals that break them and have them be reborn anew. (And many more).
Poor leaders delay providing those opportunities until they have enough money/time/things have calmed down/things have picked up/etc.
Good enough leaders provide all of these opportunities to their teams, without letting circumstances get in the way.
Great leaders invest in these things themselves. They will model the work.
(And imagine the impact it has when the good enough leader's team notices that their leader isn't taking on the same work he's suggesting they take on).
To create powerful leadership, do your work first.
Hire a coach.
Go to experiential workshops.
Take on impossible goals that break you and have you reborn anew.
No more information needed.
No more excuses.