Easy Instant Pot Clam Chowder

Name: Easy Instant Pot Clam Chowder
Ingredients: 4 slices bacon (chopped); 3 tablespoons butter; 1/2 onion (chopped); 2 stalks celery (chopped); 1 small carrot (chopped); 2 cloves garlic (minced); 1 1/2 teaspoons salt; 1/2 teaspoon ground black pepper; 3 cups gold potatoes (skinned and diced (about 1.25 pounds)); 3 sprigs fresh thyme; 2 cups water (or clam juice & reserved clam juice); 13 oz chopped clams (juice reserved, 2 - 6.5 oz cans); 1 1/2 cups heavy cream; 1 tablespoon cornstarch mixed with 1 tablespoon cold water (optional)