Add 4 cups of water to the inner pot of the Instant Pot and spice packet that came with or you can make your own. Place trivet above water and place corned beef brisket on top of trivet fat side up.
Homemade Pickling Spices (1 tsp yellow mustard seeds, 1 tsp whole black peppercorns, 1 tsp coriander seeds, 1/2 tsp whole allspice, 3 whole cloves, 3 bay leaves)