Prepare Lemon Cake Batter: Make the lemon cake batter according to the instructions on the back of the box of lemon cake mix.
Add Batter To Bundt Pan: Spray a 6-cup bundt cake pan with cooking spray and pour the cake batter into the pan. Tightly cover the bundt pan with aluminum foil.
Cook for 35-Minutes: Add 1 ½ cups of water to the Instant Pot and lower the cake pan into the pot using the trivet. Close the Instant Pot, adjust the pressure release valve to 'Sealing' and set the pot to cook on 'Manual' or 'Pressure Cook', 'High Pressure' for 35 minutes.
QPR: Once the cooking time has finished, perform a QPR (quick pressure release) by immediately releasing the pressure from the pot. After the pressure has been fully released and the pin has dropped, open the pot. Carefully remove the hot bundt pan from the pot.
Let Cake Cool: Set the cake pan on a heat resistant surface and remove the foil from the top of the pan. Allow the cake to cool for 5 minutes. Unmold the cake onto a large plate and allow it to cool for another 10 minutes.
Make Glaze: Add the powdered sugar, lemon juice, butter, and lemon zest to a large measuring cup and mix until the sugar is fully dissolved.
Glaze Cake: After the cake has cooled, pour the glaze over the top of the cake to fully cover.