default or selected kernelversion does not have config value CONFIG_KEXEC_SIG_FORCE.
Result is shown for kernelversion 6.9.9

Require a valid signature in kexec_file_load() syscall

configname: CONFIG_KEXEC_SIG_FORCE

Linux Kernel Configuration
└─>Processor type and features
└─>Require a valid signature in kexec_file_load() syscall
In linux kernel since version 5.1 (release Date: 2019-05-05)  
This option makes kernel signature verification mandatory for
the kexec_file_load() syscall.