The short answer is: Yes, with the appropriate configuration and artifacts.
The longer answer:
You do not need to deploy a dedicated conductor node, but:
1) Your conductor configuration will need to be aware of the bootloader to utilize by architecture. See[0], look for settings ending with "by_arch".
2) These settings will need to point to the appropriate architecture bootloader, and potentially templates. GRUB has been reported to work fairly well, and a number of folks have reported utilizing iPXE. The downside is iPXE aarch64 binaries are sometimes not in every aarch64 distribution. iPXE.org does publish binaries you can at least test with if you so desire.[1]
3) You will need to create the nodes in ironic so they are labeled with their architecture. This is covered in our installation documentation[2], and can be set on the command line[3] with the key value of "cpu_arch".
If you run into any weird issues, please reply to the mailing list. I know some of the Ironic operators who run large arm hardware labs are on this mailing list, and may be able to offer additional insight if needed.
-Julia