Make the crust mixture. Pulse the graham crackers in a food processor or blender to make fine crumbs. Pulse in the melted butter and cinnamon until well combined.
Turn it into a crust. Press the mixture firmly into the bottom and up the sides of a 9-inch pie dish. You can use the back of a spoon or the bottom of a measuring cup to help pack the crust down.
Chill. Place the crust in the refrigerator while you prepare the filling to firm it up while you make the filling (at least 15 minutes).
Filling
Make the filling base. Whisk together the pumpkin puree, softened cream cheese, instant vanilla pudding mix, and pumpkin pie spice until smooth (I suggest using a hand mixer or a stand mixer). Stir in the milk until well incorporated.
Add some volume. Gently fold in the cool whip until well incorporated.
Fill the crust. Remove the crust from the fridge. Pour the filling into the crust and use a rubber spatula to spread it out evenly.
Chill. Cover the pie with plastic wrap and refrigerate for at least 4 hours or until the filling is set and firm.
Notes
If you want to use pre-made crusts, I would go for either a gingersnap crust or a pre-made graham cracker crust out of the pre-made crust options.