I found that Tony's slide to fascism following his PTSD and thinking he knew better than everyone else was a good character development in a show where he's not the hero. What we're missing is a 4th solo movie where he faces his fuck-ups and his selfishness, but no, he went out like a hero through sacrifice after causing it and blaming the rift on Cap (when returning from Titan).
I also found that early Steve really needed to get a better angry face, but that evolved well between Infinity War and Endgame.