default or selected kernelversion does not have config value CONFIG_MULTICORE_RAID456.
Result is shown for kernelversion 6.2.5

RAID-4/RAID-5/RAID-6 Multicore processing (EXPERIMENTAL)

configname: CONFIG_MULTICORE_RAID456

Linux Kernel Configuration
└─>Device Drivers
└─>Multiple devices driver support (RAID and LVM)
└─>RAID-4/RAID-5/RAID-6 Multicore processing (EXPERIMENTAL)
In linux kernel since version 2.6.32 (release Date: 2009-12-02)  
Enable the raid456 module to dispatch per-stripe raid operations to a
thread pool.

If unsure, say N.

depends
CONFIG_EXPERIMENTAL
CONFIG_MD
CONFIG_MD_RAID456
CONFIG_SMP