The ThrottleStop download includes links to some helpful guides to show you the basics of setting up ThrottleStop on a HX processor. Do some homework first. Post some screenshots of the FIVR and TPL windows so I can see what settings you are trying to use. I have never owned a 12600HX so I do not know what undervolt settings will work best. Search Google for your CPU model and ThrottleStop. Maybe someone else will have some suggestions of where you should start.
I would try undervolting the core and the P cache by -100 mV. When you press the Apply button in the ThrottleStop FIVR window, make sure your requested undervolt values show up in the FIVR monitoring table. If you have any problems, follow the links in my signature to make sure VBS has been disabled. Run msinfo32 to make sure it reports that Virtualization Based Security is disabled.
If -100 mV is stable, try undervolting some more. If you get a random blue screen, the CPU probably needs more voltage so undervolt less. It is all trial and error. Do not try to immediately achieve the perfect undervolt. It might take a few days while playing a variety of games before you should decide if an undervolt request is stable or not.