Should I Enable Xmp in Bios?

X.M.P. just makes sure that your RAM runs at its rated speed. It is totally fine to enable it.

Is it okay to enable XMP?

XMP, eXtreme Memory Profile, isn’t exactly overclock. It is simply a setting made by the manufactures. These setting are well within safe zone and should be enabled. As for overclocking, it is generally safe as long as you don’t have to increase the power by too much.

Should I turn off XMP?

If you dot have XMP enabled your motherboard will use default settings and likely set the ram to 2133mhz with slower timings. So yes if you want the ram to run as fast as it was designed to run enable XMP.