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

Allow ACPI methods to be inserted/replaced at run time

modulename: custom_method.ko

configname: CONFIG_ACPI_CUSTOM_METHOD

Linux Kernel Configuration
└─>Power management and ACPI options
└─>ACPI (Advanced Configuration and Power Interface) Support
└─>Allow ACPI methods to be inserted/replaced at run time
In linux kernel since version 4.2 (release Date: 2015-08-30)  
This debug facility allows ACPI AML methods to be inserted and/or
replaced without rebooting the system. For details refer to:
source code: