Its amazing that they can work out how to create something like that . . . .
If you mean the objects; they are scanned. Probably the same kinda tech they use for our race tracks
But the engine is incredibly capable; the sheer calculating capacity is mind boggling.
And they use it for a shit of a game, where someone "realistically" climbs a vertical wall like it was at some 20-30 degree slope. TBH it probably was exactly that at the modelling stage.
I've lately realised, you do not need these hyper realistic gfx for a good game - in fact most good games don't have it. But this look sells, even if the game itself is as shallow as it gets.