Download Moto G4 Plus TWRP custom recovery to start flashing custom ROMs onto your android phone. After that, you will be able to do much more than that custom ROMs too such as flashing all sorts of hacks to extend the functionality of the device and one of that is ability to overclock and underclock Moto G4 Plus.
This is the latest v3 TWRP for the Moto G4 Plus and brings additional functionality that was not available in v2.x versions of TWRP.
1) Download the latest version from here on your device (direct link)
2) Reboot to TWRP
3) Hit Install and tap the “Images…” button in the lower right
4) Browse to the location of the TWRP image on your device and select it
5) Select recovery from the partition list and swipe to flash