Place chicken breasts in Instant Pot. Sprinkle with garlic and cumin. Pour salsa over chicken.
Lock lid and set to Poultry. When cycle is compete, perform quick release or allow for slow release. Remove chicken, shred, and return to sauce. Stir in chopped cilantro. Serve with tortillas or over lettuce, and add desired toppings (avocado, cheese, tomatoes, cilantro, etc.)
For the Slow Cooker, add all ingredients and cook on Low for 4-5 hours or High for 2-3 hours. Shred the chicken.