Add carrot slices, celery slices, smashed garlic cloves, peppercorns, sprigs of rosemary and/or thyme, and plenty of sea salt to Instant Pot.
Pour in enough filtered water to fill pot ⅔ of the way. Secure lid on Instant Pot with valve in sealing position.
Set Instant Pot to cook on Manual Low Pressure for 180 minutes (see Notes below). Instant Pot will pressurize, then cook time will begin.
Once cook time is up, use Natural Release to let pressure out of Instant Pot. Process will take approximately 20 to 30 minutes. Once Instant Pot is cool enough to touch, remove lid and set aside.
Place a mesh strainer over a large bowl and gently pour broth over strainer. Discard bones and veggies. Pour broth into glass jars with tight fitting lids, or into plastic freezer bags.
Fit mesh strainer in large bowl. Carefully pour contents of Instant Pot insert into strainer. Once Instant Pot has been emptied, discard bones, vegetables, and herbs. If needed, strain broth again to remove any remaining debris or aromatics. If broth is still warm, place bowl in refrigerator until broth has cooled.
Fit glass jar with funnel if desired, or open freezer bag. Slowly pour strained broth into jar or freezer bag. Repeat with additional jars or bags as needed until all bone broth has been transferred to storage containers.
Secure lids on jars, or remove air from freezer bags and seal bags completely shut. Place broth in fridge or freezer as needed (see Notes below) or serve immediately.