Set the Instant Pot to 'Sauté' mode and heat olive oil. Add onions and cook until soft, about 7-8 minutes, then add garlic and sauté for another minute.
Cancel 'Sauté' mode. Add Arborio rice, vegetable broth, salt, and pepper to the pot. Secure the lid, set the valve to 'Seal', and cook on 'Pressure Cook' mode for 6 minutes.