Simulation is an element of D&D that grew out of its wargaming roots. Simulation in wargaming remains quite a contentious topic. Some people think sci-fi wargames can be simulations. Others don't.
My benchmark for simulation is 'can be tested against reality'. A wargame about the the Battle of the Bulge needs to be able to recreate the actual events as one of its outcomes. The effectiveness of different units needs to fall within a range of plausibility generated by our knowledge of their actual battle effectiveness. Supply limitations need to be based on actual knowledge of supply shortfalls and logistical difficulties. Movement speeds need to match the known capabilities of men and vehicles. And so on.
So if a Panther meets a Sherman Firefly at 700 yards we can have a reasonable idea - based on matters of record - of the range of outcomes and their probability in that engagement. So the stats of a Panther, relative to a Sherman - together with a gameplay loop - can be created to try and match those outcomes. You can also take the known technology of a T80 and a Challenger II and try to create a predictive model on a hypethetical conflict - but again based on the measurable reality of speeds, muzzle velocities, ammo loadouts, gun traverse speeds, targeting systems, smoke dispensors.