Add the boba/tapioca pearls, sugar, ground cinnamon, and rice milk to the Instant Pot. Gently mix.
Close the Instant Pot. Make sure the sealing ring is in place and set the vent to the sealing position. Press the pressure cook/ manual button and set the cooking time as 3 minutes at high pressure. When the cooking is complete, let the pressure release naturally. Carefully open the Instant Pot.
Remove the inner pot and gently mix the ingredients and then strain the mixture to collect the boba. Reserve the collected boba.
Now add the condensed milk to the warm horchata and mix well. Allow it to cool.
Serving:add two tablespoons or the required amount of boba in a glass and then add the chilled horchata. If desired, sprinkle some cinnamon and serve it.