Commodore 64 has a fixed 16 color palette, but there is no universal one. Due to resistor variances of VIC-II chip on the Commodore 64, there are variation from one machine to another. I prefer to use the Pepto palette.
More info about the Pepto palette:
https://www.pepto.de/projects/colorvic/2001/
Some other palettes for comparison:

VIC II

CCS64

Pixcen


