In the Instant Pot™, add chicken, onion, corn, black beans, salsa, chicken broth and seasoning, stirring to combine.
Secure lid; set pressure valve to SEALING. Select MANUAL or PRESSURE COOK; cook on high pressure 5 minutes. Select CANCEL. Keep pressure valve in SEALING position to release pressure naturally for 15 minutes. Carefully release remaining pressure, and remove cover. Stir in 1/2 cup of the cheese until melted.
To serve, ladle soup into serving bowls; top with remaining cheese and remaining ingredients.