Remove messages from my iPad without affecting my iPhone or iCloud messages

I have just over 40 GB of messages in iCloud. My phone (500 GB capacity) says messages only takes 4.38 GB of storage, but my iPad (64 GB) is trying to download all 40GB of messages. How can I only have messages on my iPhone and Mac, because I never have and don't suppose I ever will text from my iPad.

I'd be willing to keep the past 30 days on my iPad, but I don't want to delete old messages from all my devices.

I tried to sign out of iCloud Messages on my iPad, then delete my messages, but ran into an issue where I cannot open the Messages app on my iPad without being signed in to iCloud