Add the broth, Greek yogurt, mayonnaise, onion powder, garlic salt, black pepper, spinach, artichokes, and cream cheese to the Instant Pot insert.
Lock the lid and turn the valve to Sealing.
Cook on High Pressure for 7 minutes.
When the timer ends, carefully quick release the pressure by turning the valve to Venting.
Open the lid and stir well.
Stir in the Parmesan and mozzarella until melted and smooth.
Optional: for a golden top, transfer the dip to an oven-safe dish and broil for 3 to 5 minutes.
Serve warm with chips, bread, crackers, or vegetables.