I have a Dell G15 5511 with an i7 11800H and RTX 3060. I was only able to undervolt by -50 mV on both Core and Cache, going any lower is stable on benchmarks but causes crashes and BSODs on some games. It looks like your CPU is not stable with -50 mV, maybe try -40 mV or -30 mV, although I don't think those values will lower temperature too much.
Other things you could try, use a laptop base with fans, this can reduce temperatures by a few degrees (around 5 degrees on average), or disable Hyperthreading, this can lower temperatures a bit or it can allow the CPU to clock higher at the same temperatures, this will reduce performance on heavily multithreaded applications that use more than 8 threads, but most applications and games will perform the same or slightly better due to higher clocks. Some game exceptions are Starfield, Cyberpunk 2077 and Uncharted Legacy of Thieves, those games like 16 threads.
Edit: Another thing you can try is undervolting the GPU using MSI Afterburner, this can lower the temperatures on the GPU, which in turn can lower the temperatures on the CPU, if they share the cooling solution of the laptop.