Annoying Sync on Apple devises

Go to your AccountSettings and/or System Preferences > iCloud and UNcheck the items you do not want to sync. Apple's default is that you want to sync. I do not sync anything. Beware though every time you do an update, you need to do it again and, when prompted, do not sign into iCloud during the setup - that is the step that makes it sync automatically.

As I said, I don't use iCloud, so I hope someone will chime in, but I wonder why you have iCloud drive on? You are also storing photos there? As far as I know, as long as it is on and you are storing files there, it will sync - at least the photos and maps. And I am not familiar with that IM transfer agent. If you do not get an answer here, contact Apple support.

Not sure about your Mail app since all of those are POP accounts which means that emails are downloaded to your computer on which the account was created on. they will not be downloaded to other devices. POP accounts are unusual nowadays, most are automatically IMAP.

You can turn off or on from the iCloud settings on each of your devices. Mail accounts are normally stored on the mail servers and are accessible from any mail app.

I can only tell you what I have and that is: Absolutely nothing is checked that has to do with iCloud except the Find My app. But, again, that is because I do not want to use it for anything.