pack a (hard/hefty/strong etc) punch(also pack a wallop) to have a very strong or impressive effect
[TahlilGaran] Dictionary of Contemporary English ▲
pack a punch v. phr.,
slang 1. To be able to give a powerful blow; have a dangerous fist.
He packed a mean punch. 2. To have a violent effect; be powerful.
It was vodka, and it packed quite a wallop. [TahlilGaran] English Idioms Dictionary ▲