If they are digital models, their surface coloring is a blend of realistic and something called "cell shade".
100% cell shaded looks very simple cartoon-like, "NIM the Invader" was all 3d models fully cell shaded.
There are many more examples, NIM was the only one I watched.
These are extraordinary, this artist is truly incredible.
However, if these are frames from animated productions he's been a part of, it isn't likely he created the entire scene. Images this complex in a TV show or movie are never done by one guy, the work is always distributed to team members that handle separate tasks.
It isn't uncommon to see a team member post images he was a part of.
I know nothing about the shows (if they are) or the artist involved, but MAN these are well done.
----After re-reading the text, Kevin Hong lives in NYC. Sounds like these are a ONE MAN creation!!
YOW!!