Select the Sauté function on an Instant Pot (or other multi-function pressure cooker). Heat the sesame oil in the pot. Add chicken thighs and saute until browned on the first side, 3 to 4 minutes. Add garlic and flip the chicken, sauteing until the other side is browned and the garlic is fragrant, 3 to 4 minutes more. Hit Cancel and transfer the chicken to a plate using tongs or a slotted spoon.