CONFIG_ARC64 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips
default or selected kernelversion does not have config value CONFIG_ARC64.
Result is shown for kernelversion 6.2.5

CONFIG_ARC64 (not configurable)

configname: CONFIG_ARC64

Linux Kernel Configuration
└─>ARC64
In linux kernel since version 2.6.12  
is depended by
CONFIG_SGI_IP28