No. Neither Intel or AMD provide microcode which meets Debian's definition of "free" so CPU microcode is non-free:

https://wiki.debian.org/Microcode

You might consider that your CPU is already running non-free microcode provided by your non-free motherboard BIOS.

If you have one of these CPUs, it's literally impossible for you not to run some non-free components.

All you're doing is exposing yourself to vulnerabilities in old microcode.