Hello,
The b450 pro carbon will be fine, but you likely will need a boot kit to update the UEFI for a 3600x, unless the vendor is willing to do it for you.
X570 is really only worth it if you have need of PCIe 4.0 now or in the future. Currently, GPUs don't need that level of bandwidth so all you are paying for is the higher idle power consumption of the X570 chipset.