To the Instant Pot, add water and place trivet inside.
Lay chicken breasts in a single layer (if using frozen make sure they are separated) and sprinkle with garlic powder, salt and pepper. Toss to coat evenly with tongs or hands.
Close the lid and set pressure vent to Sealing. Press Pressure Cook on High or Manual for 10 minutes (under 2" thickness) for fresh, or 15 minutes (over 2" thick) for fresh and frozen chicken breasts (any size).
Display will say ON, Instant Pot will take about 10 minutes to come to pressure, you will see a bit of steam coming out from a valve, then float valve will rise and countdown will begin.
After 10-15 minutes your chicken is ready, Instant Pot will beep and display will say OFF. Wait 5 minutes and do Quick Release by turning sealing valve to Venting position.
Open the lid and your chicken breasts are ready for meal prep, casseroles, salads etc. Shred or cube, and save the stock at the bottom for soup.