CONFIG_ARCH_SELECTS_KEXEC_FILE is not available for the selected architecture x86.
Result is shown for architecture loongarch

CONFIG_ARCH_SELECTS_KEXEC_FILE (not configurable)

configname: CONFIG_ARCH_SELECTS_KEXEC_FILE

Linux Kernel Configuration
└─>Kernel type and options
└─>ARCH_SELECTS_KEXEC_FILE
In linux kernel since version 4.14.327 (release Date: 2023-10-10)
selects
CONFIG_KEXEC_ELF
CONFIG_RELOCATABLE
CONFIG_HAVE_IMA_KEXEC

depends
CONFIG_KEXEC_FILE