default or selected kernelversion does not have config value CONFIG_IIO_PERIODIC_RTC_TRIGGER.
Result is shown for kernelversion 6.5.1

Periodic RTC triggers

modulename: iio-trig-periodic-rtc.ko

configname: CONFIG_IIO_PERIODIC_RTC_TRIGGER

Linux Kernel Configuration
└─>Device Drivers
└─>Staging drivers
└─>IIO staging drivers
└─>Real Time Clock
└─>Periodic RTC triggers
In linux kernel since version 2.6.32 (release Date: 2009-12-02)  
Provides support for using periodic capable real time
clocks as IIO triggers.

source code:
drivers/staging/iio/trigger/iio-trig-periodic-rtc.c