Question about Kingston FURY Renegade

I can't answer the question conclusively because I don't know what this desktop looks like inside. The SSD is m.2 (i.e. the small version and not 2.5" in size). It is NVMe (so it needs the corresponding PCI slot, not just SATA). I don't know of any PC that has several such slots. In my case, I use the SSD as a system drive. I cloned the existing system onto this disk.
All other hard disks are 2.5" SSD (SATA).
Conclusion: If the existing system disk is M.2 NVMe, you can replace it with another hard disk.

Added: The free slots mentioned can be used for interface cards. There are interface cards that can mount the required slot for M.2 hard disks.