Pour water in the Instant Pot and add cabbage. Sprinkle cabbage with garlic powder. Close the lid and turn the valve to Sealing position.
Press the "Pressure Cook" or "Manual" button and set the time to 5 minutes on High pressure for firmer cabbage (or 10 minutes for really soft cabbage).
When the Instant Pot is done cooking, quick release (QR) the steam, drain the cabbage, sprinkle with salt and pepper to taste and serve.