A different role in the game? If you wan to be more of a support PC, you have more feats than other classes. Take the leadership feat and give everyone temp HP. Maybe take the protection fighting style so you can protect allies. Fighters aren't bards, but neither is any class that isn't a bard.
If you want to open locks, take a background that gives you lock picking. Or just bash the door down, it can't be any noisier than knock which is audible up to 300 feet away.
Or that the caster can cast on the fighter if the situation calls for it. I mean you could give the fighter the ability to fly if you want, doesn't mean it would fit the theme of a mundane fighter that's just really good at fighting. In the other thread people are saying that an MCU character that matches would likely be Captain America from the MCU movies. Can Cap jump 60 feet with a running start? No.
Huh? It's called plate mail. Take the defensive fighting style and a shield to get AC 23 before magic. If you're dex based consider defensive fighting style and two weapon along with defensive duelist. In either case your AC will better than the wizard. Then again your fighter can have double the HP of that wizard, even if they do get hit more it's not a big deal. I don't see why it's a big deal.