Set Instant Pot to Sauté and add 4 tablespoons butter. Stir occasionally. Once melted, add chopped onion. Sauté approximately 4 minutes or until translucent, then add minced garlic and sauté until fragrant.
Next, add rice to Instant Pot. Stir well to thoroughly incorporate rice, completely coating it in melted butter.
Pour in white wine (or water) and add 1 pinch saffron. Stir, then simmer mixture on Sauté setting for approximately 2 to 3 minutes. Add chicken broth and stir, scraping sides of pot to dislodge any grains of rice. Let simmer 1 minute.
After 1 minute, secure lid on Instant Pot with vent in Sealing position. Set to Manual High Pressure with 6-minute cook time.
Immediately and carefully Quick Release pressure and remove lid. Stir risotto until all liquid is absorbed.. Add in Parmesan cheese, remaining butter, salt to taste, and pepper to taste. Stir until cheese is completely melted, then serve risotto warm.