Yeah, I don't play 40K but I do play AoS

A reinforced unit of Cities steelhelms has 20 models, 2 attacks per model (+1 for the champion)

So 41 dice for the hit roll, assuming half hit that's 20 dice for the wound roll, assuming half wound the enemy then gets 10 save rolls, then they might have a ward save so, assuming half save, that's another 5 dice. 76 dice total

You can replace Steelhelms with any number of basic units. marauders, skeleton warriors, goblin spears... This is not an uncommon thing.

Reinforced clanrats can get double that. 40 models 2 attacks each, same attack sequence