Add the chicken, broth, onion, Lipton seasoning, and garlic to the pot.
Place the lid on the Instant Pot and lock it. Make sure the lever is set to seal, then press the manual button and set the timer for 10 minutes.
When the time is up, let the pressure manually release for 10 minutes, then release he pressure and remove the lid.
Remove the chicken and shed it with a fork. Place the chicken back in the liquid.
Add 1/4 of the chicken to a bun and top with a slice of cheese. Repeat with the other 3 buns. Place under the broiler until the cheese is melted and the bun is toasted. Serve with a side of au jus.