No, platies are not schooling fish. However, platies are considered shoaling fish, so you should still keep platies in groups. A small group of three to five platies is perfect for a small tank.
While platies don’t form close-knitted groups like schooling fish, they still prefer to live in small groups called shoals. Shoaling fish feel safer and happier in a group, especially when there are other fish in the tank.
Even though platies are happier in groups, make sure not to overcrowd the tank. An inch of fish generally requires a gallon of water in the tank. Because platies can grow to be about two inches long, each fish needs around two or three gallons of water to live comfortably.
A 10-gallon tank should provide plenty of space for three to five platies.