No, sneak attack is a rogue class feature where once per round you can increase the damage of your attack significantly as long as you are attacking an enemy who engaged with at least one other opponent or if you have advantage on your attack roll. It scales with your rogue level and is one of the main reasons to play a rogue. It is why you usually should not multiclass a rogue if you care about optimization, as there aren’t many multiclass options that will improve the raw damage output of just being a straight rogue.
