Does the Microcenter warranty cover overclocking?

So this is a tricky subject, given how memory works. You are correct in that your processor is rated to run at 3200Mhz for memory, however this isn't exactly the case with modern DDR4 XMP profiles. You have two different types of 3200Mhz. You have the JEDEC defined standards and the XMP overclocks. JEDEC standards are defined by a council of companies that all mutually agree on specifications that their products can operate at and they design them to meet these specifications. XMP overclocking often pushes beyond these standards for more performance. Here is a list of JEDEC DDR4 standards: https://en.wikipedia.org/wiki/DDR4_SDRAM#JEDEC_standard_DDR4_module. If you look on the right hand side of that link, you will see the various DDR4 JEDEC standards and their primary timings. Common primary timings include: 3200 20-20-20, 3200 22-22-22, and 3200 24-24-24. It is important to note that these JEDEC DDR4 profiles must operate at 1.2V. Intel defines their memory controller limitations to these standards. You can find their memory controller specifications for your 11th gen processors here: https://cdrdv2.intel.com/v1/dl/getContent/634648. Details outlined in Section 2.1.

In the image above, you can see the 1.2V they are specifying.

In this image above, you can see they are defining their support for CAS Latency 22, meaning they are using the JEDEC 3200 22-22-22 standard.

Your XMP profiles on the other hand, can run much tighter timings such as 3200 CL14, with a DRAM voltage of 1.35V or higher. This will offer a significant improvement in latency performance, but does put additional stress on your CPU's memory controller and may result in system instability. Since these values operate outside of the Intel official specifications, they are not guaranteed to work like the JEDEC standard is.

To answer your question as to whether an XMP overclock would void a CPU warranty in the event of damage, the answer is yes. HOWEVER, I have been overclocking memory for over a decade now and have never killed a CPU doing it. That is not to say it is impossible, as certainly too much VCCIO/VCCSA voltage can do so, it is not something that you'll likely ever encounter by simply loading an XMP profile. Just ensure that when you load XMP, it isn't trying to set absurdly high voltages. When you load an XMP, your motherboard BIOS will tell you all of the changes it plans to commit. If you need help finding out which voltage values are too high, I am sure there are guides on this forum that can answer that, or I can answer that myself. Either way, as long as you do not damage your product as a result of overclocking, your warranty will remain intact. That G Skill kit of yours should be perfectly safe to use with your processor, so load that XMP and enjoy that performance boost!