Add the olive oil, lemon juice, paprika, turmeric, cumin, cinnamon, red pepper flakes, garlic, pepper, salt and onions to a ziploc bag, then add the chicken thighs. Seal the bag and shake it well to mix the ingredients. Place the bag in the refrigerator and marinate for at least 1 hour. The flavours develop better the longer you leave them.
Transfer the chicken into your Instant Pot. Mix to ensure even coverage. Close the lid (follow the manufacturer's guide for instructions on how to close the instant pot lid). Set the Instant Pot to the Manual setting and set the timer to 8 minutes on high pressure.
Once the Instant Pot cycle is complete, wait until the natural release cycle is complete, should take about 15 minutes. Follow the manufacturer's guide for quick release, if in a rush. Carefully unlock and remove the lid from the instant pot. Remove the chicken using a slotted spoon.
Heat the olive oil in a large skillet over medium-high heat. Add the chicken thighs to the skillet and sear them for about 1 to 2 minutes per side just until they start to brown. You may have to do this in a couple batches. This step is optional if you want to get a crispier chicken.