Throughout all of Book 3, we’ve seen Sokka’s leadership skills reach their peak level of maturity, and “Sozin’s Comet” demonstrates them nicely.
Back in “The Boiling Rock,” Sokka mentioned that he wanted to play things by ear more often because he noticed that a lot of times his extremely detailed plans that he devises ahead of time don’t exactly work out like they should. He’s learned that yes, careful planning is important, but developing a sense of flexibility and the ability to adapt to the situation is of equal importance - after all, when you’re out there fighting, you can’t ever precisely predict exactly what your enemy will do, so adapting as events unfold is a must.
This is exactly what Sokka shows mastery in during the finale:
-Left picture - Sokka, Suki, and Toph are able to get into the control room of one of the Fire Nation airships, but they need to figure out how to get rid of the rest of the crew. Sokka comes up with the brilliant/amusing idea to announcing it was someone’s birthday over the loudspeaker and consolidate all of the crew on the bomb bay doors so he could drop everyone into the water. -Middle picture - Sokka uses his intellect to come up with an ambitious plan on the spot to perform an “airship slice,” aka use their ship to ram into all the other ships, destroying everyone. It’s dangerous and stupid, but also a very clever and efficient way of taking all the airships down. -Right picture - In order to perform his airbending slice again, Sokka has the idea to have Toph metalbend the rudder to switch the airship’s direction and go backwards to ram into all the airships a second time. This shows Sokka’s quick wit in coming up with effective plans that utilize the skillsets of his team (i.e. Toph’s metalbending).
Overall, these final episodes are a testament to Sokka’s growth as a character throughout the series. He remains the rational, meticulous guy that he’s always been, but he’s learned so much around those core traits, which has shaped him into a much more versatile character who understands what true leadership is - it’s not the meticulous planning and pre-battle inspiration that matters as much as the quick decisions one makes while in the actual heat of battle to adapt and take control of the situation at hand.