In DRM info app on Asus 6z show Wide Colour Gamut not supported but specs says it is DCI-P3 screen where as on Redmi k20 pro app shows wide colour gamut supported.
I honestly have no idea why you're not seeing Wide Color Gamut. It should work if you have set your colors to either Customized or Wide color gamut. It could be that you have some other app that's interfering with the colors.