XMP sets it to the advertised specs of your memory kit assuming you use that setting of the usual two available (one is usually a slower setting.) Manually setting the timings require that you set the memory speed (2933 for your 2x16GB kit) and either leave the memory timings on automatic after setting speed or you can manually input the timings as advertised and then set the voltage 1.35v for 2933 if the mtoherboard didn't already set it to 1.35v.
If your memory kit has an XMP setting for 2933 or 3000, I would suggest setting that first, instead of manually changing the settings. If it has issues at 2933/3000, you will have to manually set the memory to 2666MT/s
In the bios, the memory is displayed as the effective speed already. So if you set 3200, it actually is 1600, but displayed as 3200 in the bios and 1600 in a program like CPU-Z. If you were to manually set it to 1600 in bios for a 3200 kit, it would actually be 800. 2133 (1066) is the default base speed for DDR4.