Is there a way to query max root signature size?

I have read the max root signature size is 64 DWORDS. It is basically 64 on NVIDIA and 13 on AMD. But I got this info from a person working at AMD. I can't do this for every vendor out there :P. There has to be a better way to query the max root size through the API without the need to contact a person working in the company. So is there a way to find out the actual max root signature size for the active GPU? Thank you