In a small bowl, mix together the corn starch, sea salt, and ⅔ cup white granulated sugar. Set aside.
In a medium-size bowl, place the room temperature cream cheese. Break it up with a fork. Using an electric hand mixer, beat the cream cheese for about 15 seconds using Low speed. You do not want to incorporate a lot of air into the cream cheese, simply make it smooth. Add half of the sugar mixture and beat on Low speed, for about 30 seconds, until incorporated. Add the rest of the sugar mixture and beat on Low for 30 seconds.
Add sour cream and vanilla to the cream cheese mixture. Beat on Low for about 1 minute.
Add the room temperature eggs, beating on Low for about 30 seconds, or until well incorporated. Do not overmix.
Pour batter into the prepared pan with graham cracker crust.
Place trivet into the inner pot of the Instant Pot, making sure the "feet" are down. Pour one cup cold water over the trivet.
Place the cheesecake pan on top of the trivet. Close the lid with the valve in the "sealed" position. Set Instant Pot to High Pressure for 28 minutes followed by 10 minutes natural release.
Open lid gradually. Using hot pads or mitts, lift the trivet and cheesecake out of the Instant Pot and place on a cooling rack or heat resistant plate.
Absorb any condensation that might have dripped onto the surface when you removed the lid, by lightly tapping it with a soft paper towel to absorb that water. Allow cooling for about 15 minutes before adding the topping to the still warm cheesecake.