Add the drained kidney beans, pinto beans, and black beans to the Instant Pot. Then, add the diced onions, green bell peppers, and minced garlic on top. Sprinkle in the chili powder, cumin, oregano, bay leaf, and sea salt.
Pour in the chicken broth and tomato sauce, stirring everything to combine.
Place the chicken breasts on top of the mixture, making sure they are fully submerged in the liquid.
Lock the lid and set it to cook on high pressure for 10 minutes. Once the cooking time is complete, allow the pressure to release naturally for 10 minutes, then perform a quick pressure release by turning the valve to venting. Remove the lid carefully.
Take out the chicken breasts and shred them using two forks or a hand mixer, depending on your preferred texture.
Stir the shredded chicken back into the pot and let it sit for at least 10 minutes (or longer if you can) to allow the flavors to meld.
Ladle the chili into bowls and add your favorite toppings, like cheese, sour cream, or cilantro. Enjoy with cornbread or tortilla chips!