What is the point of saving (all) your messages to iCloud if you cannot access or trim the content there? They will soon use up all your iCloud storage and you will have no way to reduce their footprint - the only option will be to delete them ALL from iCloud. If you delete them ALL (so you can restore some of your iCloud storage), will messages be lost on your device as well?
iPhone 12, iOS 18
You manage them on your device. If you do not have any desire to sync them with any other device or to restore , then turn off Messages in iCloud. You also have many options in Settings for managing your storage for Messages in iCloud, such as how long you want to keep them and also a section to manage storage. In the Messages app, you can remove attachments, such as photos, that are included in a conversation to reduce the amount of storage. Not sure where you got the idea that your only option is to delete all messages from iCloud.
Messages are accessed on your device. Delete any messages that you wish there.
How to reduce footprint of messages saved to iCloud?
