Buying a Kit of 3600MHz RAM does not make it any easier to achieve 3200MHz. Both are OC RAM and will require Bios intervention for Timings and Voltage. You would pay more for 3600MHz RAM for being binned higher and there's no guarantee you would achieve 3600MHz. It will depend on the strength of the IMC (Integrated memory controller) on the CPU which will ultimately determine what frequency you will achieve.
With OC RAM you should select a kit that are tested in conjunction with the MB and be prepared to Overclock them manually in Bios to achieve their rated frequency. They will not be Plug and Play as many hope for.
During the POST (Power on self test) your RAM will be interrogated and a safe set of values to make them work are assigned. Unless you have enabled a profile to match such as XMP or DOCP the system will default to lower than the rated frequency of what they are capable of.
Here is your Motherboard QVL and it is from this you should choose your Kit:
https://dlcdnets.asus.com/pub/ASUS/...or_3rd_Gen_AMD_Ryzen_Processors_X570_0722.pdf
Of the kits I have tried I have found best results with G.Skill at 3200MHz with CL14.
This seems the sweet spot for Ryzen as many others will agree.
There is no difference in performance using a 3600MHz kit with looser timings say 16-19-19-39 and a 3200MHz kit with tighter timings say 14-14-14-34