As Lead Character artist on Civilization VI, I had the pleasure of working on a variety of leaders. All in all 30 of the 36 were done by myself personally, and though I would love to feature all 36 I am picking the top few that I think show a nice range of what Civ has to offer. 60k tris, two sets of 2k textures.
https://www.artstation.com/artwork/lk00J
https://www.artstation.com/artwork/R91Ae
https://www.artstation.com/artwork/DbZry
https://www.artstation.com/artwork/O6n86
https://www.artstation.com/artwork/lR5rgV
https://www.artstation.com/artwork/Y0mOY