Deleting files from iPhone to open memory

Welcome, -Boots, to Apple Support Communities!

We see that your iPhone storage is very full, so you tried to store some of your big attachments (email or iMessage?) in iCloud Drive, while not having them remain on your iPhone.

Unfortunately, the way most of the Apps are designed, they retain versions of the files on your device, as well as placing them on iCloud. (Some have interpreted this, along with the way Apple used the iCloud in its early days, to mean that iCloud is only a “syncing” service. That’s not strictly true, but it’s not always too far from the effective behaviors.)

As a result, simply adding files to iCloud Drive doesn’t remove them from your device.

On the subject of your nearly full iPhone storage, is a great deal of the storage taken up by what is called “Other” (check Settings->General->iPhone Storage)?

(The “Other” category of storage is simply a “catch all” category for anything that doesn’t belong in any of the other named categories.)

What version of iOS is running on your iPhone?

You should (probably) follow the instructions in the document Clear Other storage on your iPhone or iPad - Apple Support, including making sure your iPhone is updated to the latest version of iOS.

Check out this article for ways to save storage. How to check the storage on your iPhone, iPad, and iPod touch - Apple Support

How much free space do you have on iCloud? Also, have you left it charging and on Wi-Fi without battery saver mode for some time?