(5e) IYO how realistic is it for a lvl3 party do defeat a 100 HP standard brown bear?

So I'm trying to make a decently hard dungeon, and from my experience players are much stronger than a monster's CR would have you believe.

There have been "weaker" parties that could still pull a 30-40 DMG per round, and there have been parties where a single character could match that.

So I'm curious, for like a dungeon baseline, what do you think: can a party of 4 lvl3 players defeat a standard Brown Bear stat block with a 100 HP and possibly an AOE attack that imposes the frightened condition (DC under 14- the specific save doesn't matter because you can never tell who's gonna be in a party)