You can overclock pretty much anything, if you know what you're doing. As for rams, they are generally capable of overclocking but the quality of the ram will dictate how ell the overclock can and will be. You could probably be able to tighten the timings while leaving the advertised DDR4-3200MHz speeds intact while it's also possible that you could have loose timings but chase a higher frequency number.
What is the make and model of your ram kit, the motherboard and your PSU? Also, it's a good idea to make sure your motherboard's BIOS is on the latest version.