You can check a cooler, but the airline has a say.

Yes, but only if it fits the size and weight limits, and you follow the rules on what’s inside.

A hard-sided cooler works as a suitcase if it’s under the airline’s checked bag dimensions (usually 62 linear inches total). The real headache is what’s in it. If you’re packing food, it can’t be liquid or semi-liquid in large amounts (no soup, no marinated meats) unless you freeze it solid—but then you’ve got melting issues. Dry ice is allowed for perishables, but most airlines cap it at 2 kg (4.4 lbs) per bag and require it to be marked. Gel