Oh, I haven’t played as much of it as I would like yet (because I have a young kid who gets me up in the middle of the night still, and I mentally can’t get into a fast paced realtime game when I only have a few moments for gaming here and there) but Age of Empires 4 did to the Age of Empires 2 formula exactly what I wish Civ had done instead.
AOE2 was very much like Civ IV or V. Every faction had the same roster, give or take a couple units, and some minor bonuses that adjusted how they do things. Civ IV civs were barely different from each other (a unique unit, a unique building, and the leader’s two traits, IIRC?) while Civ V had Venice, which was pretty dang different, but not much else. Civ VI experimented with slightly more differentiated Civ traits and leaders having more unique to them too.
What AOE 4 did and what I would have loved to see Civ VII do is go all in on differentiating Civs. Each Civ has unique resources, multiple unique units (in fact each Civ might have its own full roster?) and unique mechanics (Mongols can move their town centers, Chinese have a unique Tax Collector who goes around their buildings and boosts them, HRE gains bonuses for having farms around churches, etc).
I think Civ could do something similar without going quite as far. For example you could have “classes” of Civs - Nomads (Huns, Mongols, Scythians), Maritime (Venice, Polynesia, etc), and so on; these classes could unlock unique mechanics and unit trees; and then individual Civs could give their class a unique spin.
I also wish they went heavier on the alt history aspect. Instead of Romans having a Legion replacement for the Swordsman, I’d have loved it if Romans had boosted heavy infantry. Before Iron Working and Swordsmen, maybe their Ancient era unit is replaced with a Hastati, and then you get your Legion, and then with Steel/Longswordsmen you get a Praetorian or Heavy Legionnaire or whatever; and then with Gunpowder your Musketmen are unique too (“what would the Roman legion have done with guns if they had them?”), all the way to unique Roman modern infantry units.
Meanwhile maybe the Aztecs buff their light infantry so in the modern era we get mechanized infantry with slight bonuses and an Eagle Warrior motif.