Yes, unlike fresh chicken breasts, you can cook frozen chicken breasts directly on the bottom of your Instant Pot without using a trivet. In that case, add a cup of water or chicken broth and season generously with salt and pepper. Frozen chicken breasts that are roughly 8 to 10 ounces each and are NOT stuck together should cook in about 10 to 12 minutes with a 10-minute natural release. This will vary if your chicken breasts are stuck together in a frozen clump, or if you're cooking larger breasts. Be sure to use a meat thermometer and check that the internal temperature has reached 165ºF. You can always add another minute or two of cooking (with a quick release the second time) if needed.