Ice packs work if you pre-chill.

Yes, but it’s not magic.

The biggest mistake people make is putting warm drinks into a cooler with cold packs and expecting hours of cold. Ice packs have less thermal mass than ice (no melting phase change), so you need to start cold. Put your drinks in the fridge overnight. Also chill the cooler itself — store it in a cool place or throw a bag of ice in it for an hour before packing.

Use as many ice packs as you can fit. Pack the cooler tight — air space is the enemy. And don’t open it more than you have to. A good rotomolded cooler helps, but even a cheap one can work if you follow those rules.

A cooler is just an insulator. It doesn’t make things cold, it only slows down warming.