Scale is a little different from graphics. I can't say GTA 5 when held under a microscope has much better graphics than other games that came out at the tail end of the gen. As far as scale goes definitely along with Skyrim and RDR its very impressive
Well, scale and sadboxy-ness impose a lot more performance costs and complications, so it makes every achievemnts much more impressive. But it trully is hard to weight scope vs. detail.
If you were to put games in distinct categories though (like weight classes in combat sports) we could divide them in order of technical complexity created by scope/scale/freedom like this:
-2D games (mostly hand-crafted art);
-Fighting games;
-2.5D platformers and top down games (3d graphis with very constrained/predictable cameras);
-Free roam linear 3D games and racers;
-Open World games;
-Free roam Space Sims;
-Roy (full simulation of the universe in VR)
In GTAV's category, it pulls no punches in terms of abition while still having asset detail at least in the same league if not better than many games that are trying to do less.
GTA has fully explorable world, no well masked invisible walls, seamless interior/exterior integration, full dinamic ToD and weather with realistic sun shadow tragectories, and it lets you both walk at a slow pace throught that world right close to everything but also fly through it at speed (real strain on streaming).
While on foot the world is highly interactive: many NPCs with high quality animations and phyics (for the time) and many physically simulated 3D objects. But you can also fly high enough that you can see the entire map on screen at once, and fall back down at reasonable speed without a hitch from the game and relatively discrete LOD transitions.
It tacled both Interior and exterior Urban environments, Forests, Farms, Deserts, Mountains, Rivers, Under Water etc... It does all of them very servicibly, and no city that gen looks as plausible and rich in its execution as Los Santos (no building fucking repeats ever)
I have deep respects fot Rockstars achievements there.