How to create a Low Power RTOS system code em C++ for ARM Cortex-M MCUs, a nRF52840?

Good night,

I am developing a Firmware for a nRF52840 created by RAKWireless RAK4631, with VSCode/Platformio/C++/FreeRTOS, and now I am changing the Architecture from a Super Loop to a Event Driven.  The events will be, for example, a accelerometer that it will create some Interruption when the acceleration reach a specific level.

Now the challenge is to reduce the power consumption with a Low Power Architecture, with resources as sleep/deep sleep and tickless, based on the "4.3.6 System Control Register" in the "Cortex-M4 Devices Generic User Guide".

Where could I find some example about the subject described above?

Cláudio Rosa