CONFIG_BIG_ENDIAN is not available for thedefaultarchitecture x86.
Result is shown for architecture sh64
default or selected kernelversion does not have config value CONFIG_BIG_ENDIAN.
Result is shown for kernelversion 5.4.123

Big-Endian

configname: CONFIG_BIG_ENDIAN

Endianness
└─>Big-Endian
In linux kernel since version 2.6.12