In the Instant Pot, combine potatoes, chicken broth, butter, onion, garlic, salt, and pepper.
Close and seal the lid. Set to high pressure for 8 minutes, followed by a 10-minute natural pressure release.
Carefully vent any remaining pressure. Remove the lid.
Using an immersion blender, blend the soup until smooth. Alternatively, carefully transfer the soup to a regular blender and blend until smooth.
Stir in the heavy cream and sour cream.
Serve hot, garnished with bacon, cheddar cheese, and chives.