Technically, you do not HAVE to use the trivet when cooking chicken thighs in the Instant Pot. However, it is helpful for preventing the burn notice from appearing. All Instant Pot's are different. Our older Instant Pot is much less finicky when it comes to trivets and we usually don't use one when making Instant Pot Chicken Thighs. However, our new one almost always gets the burn notice, so a trivet is a must!