Zardnaar
Legend
People seriously underestimate how advanced Rome was culturally and technologically. They had invented a primitive steam engine, and had Greek and Arabic math's and philosophy at their disposal that led to engineering, technical, literary, and societal accomplishments that were not seen again till the renaissance nearly one and a half thousand years later.
That thousand year gap was called the Dark ages for a reason. It was dominated by feudal bondage obligations, serfdom and thousands of squabbling warlords.
No DnD setting is based on a a feudal or medieval baseline that I know of. Not Krynn, not Faerun, not Eberron, not Mystara, not Greyhawk and not Blackmoor.
Athas is post apocalyptic really, but it's its own thing.
DnD settings tend to mirror either Golden Age Rome or renaissance/ early industrial Europe sometime after the fall of the Holy Roman Empire and the rise of Nation States, with a free working class, private armies, limited - or even quite sophisticated - democracy, market economies, modern notions of ethics and justice, advanced sewage, plumbing, and medicine, nation States with clear national boundaries and so forth.
Rome also invented apartments.
I don't expect realistic in D&D but plausible yeah.
So if you have a million person city with fast food replication using magic you could do that but wouldn't be