Any way to get full RGB color over HDMI when using Kodi on Pi3?

So I’ve installed the latest version of DietPi aarch64 on a Raspberry Pi 3, it’s great to use Kodi with HDMI-CEC and use my remote in my TV, and a large drive full of stuff to watch, my only issue is that i got spoiled with having full RGB color on my other devices, but in here, Kodi doesn’t have the option to enable it so colors really look well and not washed out.

I’ve read online that I can set hdmi_pixel_encoding to 2 in /boot/config.txt to enable it, but for some reason, after doing that and rebooting, it had no effect in DietPi, so that’s why I’m asking. Any way to get full RGB color please? thanks in advance for such a great system!