Beat the cream cheese, eggs, vanilla, heavy cream, and sugar until just smooth. Divide the batter between two bowls.
To one bowl, add the red velvet cake mix and red food coloring; mix until evenly colored. Leave the second bowl plain.
Combine the graham cracker crumbs, sugar, and melted butter for the crust.
Line the bottom of a 7-inch springform pan with parchment and lightly spray with non-stick spray. Press the crust firmly into the base.
Spoon in white batter to half-fill the pan. Drop ¼ cup red velvet batter into the center, then ¼ cup white batter on top, alternating until the pan is full.
Drag a toothpick or skewer from the center outward to make straight lines, then draw a slow clockwise spiral from the center out to marble the colors.
Pour 1½ cups water into the Instant Pot. Set the pan on the trivet and lower it into the pot using the handles.
Lock the lid and seal the valve. Cook on High Pressure for 45 minutes, then allow a natural release for at least 10 minutes.
Carefully remove the trivet with hot pads. Cool to room temperature, then refrigerate at least 6 hours or overnight.
Add toppings, slice, and serve.