Set aside corn, chard, zucchini and basil. Add everything else to Instant Pot. Lock the lid and set to high pressure for 20 minutes. When done, carefully release steam.
Stir in zucchini and corn. Close lid, lock and set to high pressure for 5 minutes. When done, carefully release steam.
Stir in chard. Close lid, lock and set to high pressure for 2 minutes. When done, carefully release steam.
Divide soup into bowls and garnish with additional fresh basil. Enjoy!