2015-2017 had some real bangers that hold up incredibly well. With mods they can look even better.
Crysis 3 easily for detail. The environments were straight up stunning and the character models are still among the best I've seen.
Arkham Knight, the asset king. Not just the insane environment detail, but even secondary characters models were extremely detailed.
The Witcher II: Wild Hunt - Not just a massive open world but a meticulously crafted one.
Dishonored 2 - While probably technically not as impressive as a lot of games even the year it released, the art design in this game was bananas. An entire mansion that transforms where you can see all the mechanisms used in the transformation with no clipping pieces was one of the highlights. Everything in this game looked like it was crafted by an architect.
MGS:V The Phantom Pain - In the right weather conditions this game often looked photorealistic, immediately followed by something goofy as hell.
Mad Max - This is often overlooked and while it does re-use assets a lot, the atmosphere in the game was spot-on and the lighting was really good.
Deus Ex: Mankind Divided - Tons of effort into making each part of the game feel entirely unique. Artists were working overtime on this one (don't tell Jason)
There were so many great looking games in that short span I could keep posting images all day. Battlefront, Doom 2016, Forza Horizon 3, Hitman, etc