Rinse the long-grain brown rice under cold running water in a fine-mesh sieve until the water runs clear.
Place the rinsed rice into the Instant Pot and add cold water (or vegetable broth), salt, and olive oil if using.
Secure the lid and set the vent to Sealing. Select Manual/Pressure Cook on High Pressure for 22 minutes.
Allow the pressure to release naturally for 10–15 minutes, then carefully switch the vent to Venting to release any remaining pressure.
Open the lid away from your face and fluff the rice with a fork. Serve immediately or store leftovers in an airtight container.