Add olive oil, onion, garlic, red curry paste, brown sugar, lime juice, soy sauce, salt, coconut milk and chicken to Instant Pot in that order. Place lid on Instant Pot and make sure valve is set to seal.
Press the pressure cook button and set to high, then cook for 3 minutes. Instant Pot will take about 10-15 minutes to come to pressure then pressure cook the 3 minutes.
Meanwhile, cook rice, water and butter in a rice cooker. Mix 1 tbsp cornstarch and 1 tbsp water together in a small bowl.
Do a quick release of the pressure on the Instant Pot by flicking the switch at the top with a spoon. Open the lid when pressure gauge has dropped and the lid opens easily.
Add in bell peppers and stir. Place lid on Instant Pot and let sit for 5-10 minutes so peppers soften. Open lid and stir in cornstarch slurry, mixing well to combine.
Serve red curry chicken with rice and garnish with cilantro. Enjoy!