Set Instant Pot to sauté mode and add vegetable oil. When the oil is heated, add the onions and sauté until translucent, around 5 minutes. Add the garlic and sauté for one minute.
Turn off Instant Pot and add chicken broth and water. Scrape the bottom of the pan with a spatula to deglaze.
Season the liquid with taco seasoning.
Add the chicken, tomatoes with chilies, chili beans, and corn. Stir to combine.
Place the lid on the Instant Pot and set to pressure cook for 30 minutes. When the cook time is up, allow to naturally release pressure for 10 minutes, then do a quick release to release remaining pressure.
Remove the lid from the Instant Pot and remove the chicken breast. Shred the chicken and place it back in the pot. Stir and serve.