Add chicken stock, rice, chicken breast, bell peppers, and onion into the Instant Pot insert.
Sprinkle fajita seasoning, paprika and salt on top, making sure to not mix in.
Cover, turn the valve to sealing position, set to high pressure, pressure cook (or manual) for 4 minutes.
When done, perform a quick pressure release, open the lid and then stir in cheese, salsa and sour cream. Place the lod back on let and let it stand for 5 minutes before serving.