Here's a shot from Recettear, where everyone except the player characters and any items are 3D models.
I was gonna suggest a pic showing the infamous vintage ham sandwich line◊ from the game, but the dungeon image is clearer.
Recettear immediately came to mind for me. Some of the monsters are 3D polygons reminiscent of PS1 era graphics, and they stand in pretty stark contrast to the 2D sprite characters. I can load up the game dig up some screenshots.
FFT is also an option, but IMO it should be from the PSX original, not the remake, and those are hard to find. (One thing I like about the Breath of Fire IV one I found is if you look closely, you might notice how the characters look slightly out of angle with the camera.)
Meh. I tried looking up skills that would show it better from Neptunia, but I don't have a DVR and the only YouTube videos I could find used the custom image feature to change the 2D art into the rage face memes, which is against this site's rules.
That's ... not too bad, actually. There's obviously a different graphical style between the polygonal monster and sprited party members. Seems cropped a bit tight though....
(Which is the same thing as I liked about the BOF 4 image I found ... the large dragon is clearly a polygonal render while the characters are clearly sprites)