It depends. C2C gives combat bonuses for surrounding and ZoC effects as well, but (most) ranged units can't fire and move so there's (theoretically, by which I mean MP, the AI is not good at C2C) incentive to break doomstacks into several smaller but not trivially eliminatable groups with possibly artillery in the rear to fire at range 2 or more. There's also stealth and ambush mechanics in play so you could have a ranged stack sit concealed somewhere to fire on a stack as it passes or have them pretend to be barbs and harass enemy patrols.
It helps that C2C has automation modes for a lot of micro too; beyond exploring you can set units, or stacks of units, to automatically hunt anything they can attack, or patrol your cultural borders.
Erebus meanwhile mixes it up with magic, which has a variety of effects that can swing combat odds in a variety of ways; big summons do more damage but grant XP to the defenders, fireballs can't kill but deal collateral damage, buffs, debuffs, healing, temporary fort bonuses, all sorts of stuff. Greater unit variety and ability promos mix stack composition and erosion up as well since it's possible to manipulate which unit actually defends against an attack rather than always getting the worst matchup for the attacker.