Drool is mostly a matter of lip anatomy, not personality or size. Breeds with loose, pendulous upper lips — the flews — cannot hold saliva in, so it pools and drips. Mastiffs, Saint Bernards, Bloodhounds, Newfoundlands and Bulldogs all share that build. Breeds with tight lips that meet cleanly at the jaw keep saliva where it belongs, which is why Poodles, Whippets, Border Collies, Basenjis and most terriers stay dry regardless of how large they are.
That means low-drool is predictable from the face rather than the breed name, and it is worth looking at the mouth of any dog you are considering. Tight flews, dry corners, no visible pooling when the dog is relaxed.
Even a naturally dry-mouthed dog drools in three situations, and none of them indicate a problem: anticipating food, feeling car-sick, and panting hard after exercise. What is worth attention is a sudden change. A dog that has never drooled and suddenly starts is telling you something — dental disease, a foreign object lodged in the mouth, nausea, or in rare cases a swallowing problem. Persistent new drooling is a reason to call a vet, not a reason to buy more towels.
For heavy droolers there is no fix, only management: a bib-style bandana, a wipe-down cloth at the door, and washable covers on anything the dog leans against.