Place chicken breasts in Instant Pot, then pour in broth. Sprinkle with the taco seasoning, then add in diced tomatoes.
Set to Poultry/Meat for 12 minutes, then manually release steam before removing lid.
Remove chicken breasts from Instant Pot and shred with two forks. Place shredded chicken back into Instant Pot and stir to mix in with the sauce.
Fill tortillas with shredded chicken and any toppings you'd like.