Place the bones in the Instant Pot. The exact amount of bones used is not critical. Don't fuss too much making sure it is 2-3 pounds of bones. One chicken carcass is all you need.
Add in the celery, carrots, onions, garlic, apple cider vinegar, peppercorns and salt.
Fill the liner with water to the MAX fill line.
Lock the lid onto the Instant Pot and set the steam release knob to the “sealing” position. Press the “soup” button and set your Instant Pot for high pressure for 90 minutes. You can also use the manual button, but the soup button is designed to great a clear broth. It will take about 15-30 minutes for the Instant Pot to come to full pressure.
Once the pressure cycle is complete, allow the pot to naturally depressurize for 20 minutes. Since the pot is very full, doing a quick release may cause spurting. If you decide to do quick release, add 20 minutes to your pressure time.
Strain out the bones and vegetables from the broth.
Allow the broth to fully cool before placing in the fridge or freezer.