Yes, but if you compare the complexity of (Turbo) Pascal to the complexity of C++... language, environment, libraries and cross-compilation...
(A nice thought-experiment is to ask if Quake could have been coded in TP at all - even if memory hadn't been an issue (I think there was no DOS extender for TP, but I could be wrong).)
In the storm of Doom-Quake mania of the mid 90s there was Chasm: The Rift by a small Ukrainian company Action Forms. And if memory serves me right, it was created in Turbo Pascal. It was late in development and came out in 1997 after Quake, so it didn't get much traction. But the engine, though pretty limited, could produce 3D enemies with interesting effects not found even in Quake.
So Turbo Pascal (with a whole bunch of x86 asm inclusions) was totally capable of producing Quake-level games. I myself, in the late 90s, discovered the hidden capacities when I learned x86 assembly from Peter Abel's book. Once I got rid of the primitive TP BGI library and switched to VGA 13h, it was an unbelievable level up in abilities to manipulate pixels on the screen!
> Chasm: The Rift
I might be misremembering but I thought it was more of a Doom-style engine with 3d models instead of sprites for the entities, rather than a full 3d engine like Quake.
It was definitely something unorthodox - I remember being confused about how it actually worked.
The first time I played, I thought "It is just like Quake". Then you start to notice that the levels are pretty limited - it is all narrow corridors with rare small chambers and open spaces, no steep elevation changes, no rooms above rooms... Kinda like Doom. But then, father's examination shows sloped surfaces, shelves and bridges - stuff the Doom engine can't do.
Maybe, for level geometry, it is closer to portal rendering engines like Build. Still looks pretty claustrophobic even compared to Doom and Duke Nukem 3D. I feel the Chasm level designers could've got more variety from that technology, but again, maybe that was some fundamental limitation. Or maybe it is just like FPS were designed in the mid 90s.
Monsters, items and weapons are fully 3D, though. With dynamic lighting!
I don't see why it couldn't have been written in Pascal. Plus, Quake was written in C/asm, not C++.