Chop veggies into about 1/2-inch cubes and set them aside.
Set Instant Pot to saute and let it heat up. Add oil.
Saute onion and celery until starts to golden.
Smash garlic and add it to the pot. Saute until fragrant.
Add squash and potatoes, stir, and saute for a few minutes.
Add sage, salt, and chicken stock.
Stir and close the lid and make sure it's latched. Turn the valve to "seal" and set the Instant Pot to pressure cook on high pressure cook mode for 15 minutes.
Let it do a natural release for about 10 minutes. Be careful opening the lid.
Transfer everything into a blender but don't add all of the broth or soup might be too runny. Set aside about 1/2 cup of broth and blend everything until smooth. Check and see if you like the consistency and if you need to add the broth that was set aside.
Add heavy cream and blend just until it's mixed in.
Serve with crackers, grilled cheese, chick peas, or croutons.