There are several "pick up and haul mods" that use a pawn's whole maximum weight for carrying. This comes out to like 800 pieces of corn.

If you don't have the mod, you can get the same effect with sufficient micromanaging. Players colloquially refer to this as megahauling. You basically set up one or two pawns on a caravan, and tell them to bring as much corn as possible. If you can't, because the corn is not yet in a storage zone, then select the pawn in the caravan, and right click the corn, and select "load into caravan". Much like the mod, this process uses the whole carry weight. As soon as they are loaded, before they leave the map, draft them and put them in the freezer, and cancel the caravan.

Do not store more corn than you need. Game difficulty is directly proportional to wealth.