So, there is no "easy" way of just resizing current partitions, even if there is plenty of free space available. Just seems so counter-intuitive.
It is a function of how partitions are created and their relationship to the physical location on the drive. Whereas APFS volumes are
logical structures and not tied to a specific physical location.
NOTE: You will not go too far astray if you think of a volume as "a folder that
mounts, and functions, like a
drive".
How do I set up such volumes? Use Disk Utility for this? I am going to want to have 3 of them: 2 for each of my Carbon Copy Cloner backups, and the third for miscellaneous items.
Yes you use Disk Utility. Once a drive is formatted APFS, when you select the Container in Disk Utility a +/- icon will be enabled on the tool bar. Selecting a plus will create a new partition and minus will delete a partition. Either option takes only a few seconds at most. There is an option to specify the size of a volume, but I strongly recommend ignoring it altogether and allow volumes to grow or shrink as needed. It is far more flexible.
OK, from what I gather, here is what I should do:
1. Launch Disk Utility.
2. Erase and Format the entire SSD as APFS.
3. Select the Container.
4. Click the "+" sign to create 3 Volumes.
5. If desired, designate a size for each volume. (If I did that, I would make each Carbon Copy Cloner backup volume 175 gig in size, and the Miscellaneous one about 150 gig).
So just to confirm, I really don't need to do #5, and the space needed for the two Carbon Copy Cloner volumes will adjust as needed.