i have a golden pearl rx and i need to know what the bottom gold color name and code? where to get t/u paint?

I don't think there is a 1999 RX paint called "Golden Pearl". Are you sure it's not "White Pearl" which is actually a golden color? Check the 3 digit paint color code on the drivers side door. All the colors are here:
https://www.clublexus.com/forums/rx-...ication-2.html

Lexus refers to the RX300 white color as Golden Pearl. The paint code is 057. The associated lower cladding color doesn't necessarily have a name to it but it does have a color code of UCAA6. Both colors, we have available and you're welcome to contact us directly to order.