Al, thanks so much for your prompt response, especially over a holiday! I hope you found it warm and happy.
This is weird. I own three Apple devices: an iPad Pro, a MacBook Air, and the iPhone 7. If I log into iCloud from either the iPad or the MacBook, I'm given immediate access to my data for that device, with no prompt to accept new terms. Digging through My Account, I find no settings in either device that refer to updating new terms. It is only the iPhone that has this prompt, and while it does let me access iCloud from the phone Files app, it gives me access only to files from the iPhone on iCloud. So I can't transfer files between devices, and Air Drop is problematic on my systems. Is there some flag set somewhere on the iPhone software that sets up this notification? Thanks again for your help.