The Small Sip Potion is classified as a rare pet potion in Adopt Me! that be found in the Potion Shop next to the Big Brew Potion. It is priced at 250 and was released with the Magic Update on January 18, 2020.
Similar to the other pet potions, the effects are only extended to pets. Once fed, the pet will shrink to a slightly smaller size for 10 minutes.