Tony was done after Endgame, dude was pushing 50. He ain't showing up until Doomsday. He really didn't even wanted to fight in Endgame but was dragged into it cause it was a way to bring back his Dead adopted son.

Mostly, people believed that Stark was someone who would never sacrifice himself for someone else (as Cap said). Apparently the filmmakers wanted to show fans that Tony finally understood his mistakes (and that the heroes will also respect Iron Man) by making the ultimate sacrifice.

If Tony didn’t die he would have still gone into retirement, the Edith glasses wouldn’t have gone to Peter. Far From Home would have a different story sorta

Tony could have shown up briefly to interact with Riri

Steve’s death would be emotional like Tony’s

I guess before him passing he would have still passed the mantle to Sam

Sam and Bucky would have more of an emotional effects after his death. Not sure if it would change their arcs

About Steve, I believe the only Steve's right end is to go in his home after a war has ended, like a soldier.

It would have been way more impactful had Steve died. The reason why is because he was more of a patriotic symbol. The world celebrated Tonys sacrifice to a degree but if you look deeper, the only person truely impacted by it was Spiderman . Nobody else really dwelled on it or mentioned it after Endgame.

I feel this would not have happened if it was Steve. His death would have been referenced or easter egged alot more.