I am not sure what you mean.
I mean that unless you have an exceptional anomaly at hand, (which at that point should be clearly marked as one), a notable outlier (i.e. a magically mutated troll, way bigger and stronger than normal for plot reasons), creatures of the same type should have the same range of threat and be consistent across the game.
And there's a name for considerably older adult dragons, anyway, which is ancient dragons.
The idea that you can cross the same type of creature all across a campaign, all the way from level 2 to 20, and it keeps appearing buffed to match your party is garbage in terms of immersion and mechanics.
Conversely, even without meaningful stat changes, the idea that every time you move in a new area all creatures and critters are labeled with the level of that area (something that DOS 1 and 2 did in spades, with even rabbit and mice ranking level 17 outside of Arx) is also garbage.
"Bu-but level 17 rabbits and mice still had very few HP and died with a single hit". Precisely, which makes the fact that they had level tag even more pointless. A shitty, immersion-breaking, "gamey" expedient to railroad the player and break the illusion of being in the middle of a true adventure, rather than in a crappy level-gated MMO starting area.
