LMIC FOR STM32CubeMX in 15 minutes

Hello
Thank you all very much for the help you gave me with the comments because thanks to those I managed to do the data transmission through ABP

Now I have another problem

I want to make the microcontroller go to Sleep mode after doing a transmission every X time

I have knowledge of the sleep, standby and Stop modes of operation

my question is
In which area of ​​the Main file can I integrate some of the sleep modes?