How to properly partition a Fusion Drive on a late 2019 iMac whilst also making the first partition usable to install macOS?

Currently, my iMac has no active macOS on it. And the Fusion Drive shows up as two volumes. I am trying to come up with ways to fix the Fusion Drive, install macOS on it(but then how to make Fusion Drive APFS to make it usable as a boot drive for macOS without destroying the logical volume structure?), and then partition the Fusion Drive into three partitions. Environment: 11.5 GB partition on SSD, main contents are a base macOS recovery image (internet installer) and macOS install drive (Catalina). The rest of the SSD is a free partition (formatted in APFS). All of HDD is a free partition (formatted in APFS). Currently, I tried: 1. Fixing my Fusion Drive, then partitioning it. (Partition Fusion Drive breaks its ability to be a valid install drive for macOS, also unknown if the corestorage system still works after being partitioned.) 2. Add multiple volumes into a logical volume group to achieve multiple drives. (Currently not possible, requires older versions of diskutil.)