That's going backwards. Faster = lower numbers for timing. so running it at 8-8-8-21 or something lower will be better. However, with memory, it's often you see increasing the speed will overcome the increase latency with higher timings.
Overclocking RAM is trading higher timings (higher latency) for faster speed (measured in MHz). You can overclock RAM in the same sense that CPU's are rated by Intel/AMD to by default run at a specified speed and you go beyond that. Hence why there's DDR4 ram out there that's capable of 3200MHz when Intel processors running DDR4 by default run at 2133MHz.
To simplify things, if you buy DDR4 ram that is only rated for 2133Mhz, I would not go beyond 2133. If you dig deep enough (doing your research), sometimes there are RAM out there than can go above their rated value, but it's almost always never worth it to do so. If you want to overclock DDR4 ram, just buy them that are rated at 3000 or above. Or... just do what most people should be doing, unless the mobo BIOS can't read it properly for whatever the reason is... set your memory options in your BIOS to run off of the XMP profile.
