Can you quantify "overheating" first of all?
Unless you're seeing throttling, then you should be 'fine' to continue at those temps. A laptop, due to it's confined space & limited ability to cool, will (almost) always run hotter than a comparable desktop.
In terms of undervolting, if the option is not natively in the BIOS, then it's not something you can easily 'add'. To 'add' that functionality, you'd need a modded BIOS with all the potential hiccups that come with it.
Software would be your friend here. I believe both ThrottleStop and XTU allow you to undervolt your CPU.
I used XTU and I could see some throttling while playing games and the temperature is almost all the times near 92-93 and even the GPU.
What I did is use Throttlestop to undervolte the CPU with -0.125mV but even after doing this I still have the same issue.
I know that both GPU and CPU use the same heat pipes which can effect the CPU cooling as well.
So what to do exactly?