Place pasta, water, salt, pepper, paprika, and garlic powder in the Instant Pot. Stir well and even out the pasta to ensure it's fully submerged in the liquid.
Close the Instant Pot lid and set the steam release valve to the sealing position. Cook on Manual/Pressure Cook at high pressure for 3 minutes for whole wheat elbow pasta or 4 minutes for white elbow pasta. (As a general guideline, cook pasta for half the time listed on the box in the Instant Pot.)
While the pasta cooks, shred the cheese and warm the milk.
Once the cook time ends, quick release the pressure by moving the steam release valve to the venting position. For a slower release, move the valve gradually to reduce the starchy steam and minimize mess.
When all the steam has been released and the pin drops, open the lid and add the butter to the pot. Slowly stir in the cheese, a little at a time, followed by the milk. Taste and adjust salt and pepper if needed.
If the mac and cheese seems too liquidy, let it sit on the warm setting for a few minutes to thicken. Serve.