Remove insert from the Instant Pot. Place steel cut oats, water, brown sugar and cinnamon into the insert. Give it a gentle swirl to combine. Place the insert into the instant pot. Put the lid on and set to Sealing.
Manual, High, Adjust to 7 minutes.
Quick release, or natural release.
Open up the Instant Pot, stir the oatmeal. The oatmeal and any remaining liquid will thicken as it cools. Ladle the oatmeal into bowls and top with berries, milk and sweetener to taste.