Kathy, at this point, I am not even convinced that iCloud storage is the answer to this problem. Generally speaking, I do not like using any kind of cloud storage, whether it is Apple iCloud storage, or storage by any other online storage company. Yes, security and privacy are big issues with me. I just feel uncomfortable about storing my personal data online. There have been way too many security breaches in recent years.
A while back, I was paying a dollar a month for 50 GB of iCloud storage. However, I cancelled it, being as I wasn't really using all of that storage space.
A few days ago, right before my photos syncing broke, I disabled all of the apps in my iCloud settings in System Preferences/Internet Accounts/iCloud, except for Calendars, because I noticed that I lost a few features when I disabled the Calendar app in iCloud.
However, today I discovered that a few other things had stopped working as well when I disabled them in my iCloud settings. So I was forced to re-enable Photos, Mail, Contacts, Calendars, Notes, and Find My Mac.
But here's the thing that I really wanted to mention to you. I re-enabled the Photos app in my iCloud settings, in the hope that I would be able to get all of my photos and videos from my iMac back onto my iPhone, even if regular syncing is currently not working, as we all know.
Upon enabling the Photos app again, I got a message that there was not enough space in iCloud to accommodate all of my photos and videos. So, I went ahead and repurchased the $1/month iCloud plan so I again have 50 GB of iCloud storage.
I also verified that I have "iCloud Photos" enabled on my iPhone, which now runs iOS 13.2. I also have my iPhone set to "Download and Keep Originals". The options "Upload to My Photo Stream" and "Shared Albums" are both disabled.
So even though I have the Photos app enabled in my iCloud settings on my iMac; and even though "iCloud Photos" and "Download and Keep Originals" are enabled on my iPhone; and even though I paid for the 50 GB of iCloud storage, NONE of my photos are yet appearing on my iPhone. All I see are two photos I actually took on my iPhone, and a video I shot on my iPhone a few days ago. My 21 GB of photos and videos from my iMac are nowhere to be found in the Photos app on my iPhone.
So, before you consider purchasing extra iCloud storage space, you may want to consider the above. Quite frankly, I am rather disappointed by the various bugs and incompatibilities I have encountered since upgrading to Catalina. I had none of these problems with Mojave.