I’m not sure about the bios since I bought this laptop second handWelcome to the forums, newcomer!
The only thing you've mentioned in your thread(apart from undervolting) is that you have laptop mentioned in your thread's title and tag. Please mention the make and model of your laptop and it's SKU.
What version of ThrottleStop are you working with? Is your laptop on the latest BIOS version?
Intel removed the ability to undervolt their mobile H series processors. That is why ThrottleStop says Not Available at the top middle of the FIVR window. This feature is not locked. It no longer exists. Only the mobile HX series support undervolting.i7-13620H