Press the Sauté button on the Instant Pot and heat oil. Stir-fry onion, carrot, and celery 3–5 minutes until onions are translucent.
Add tortellini, broth, salt, and pepper. Press the Cancel button. Lock lid.
Press the Manual or Pressure Cook button and adjust time to 10 minutes. When timer beeps, let pressure release naturally for 5 minutes. Quick-release any additional pressure until float valve drops. Unlock lid. Add baby spinach and stir until wilted.