How do I move my Messages file in my Mac to an external hard drive to be opened in the Messages app later on?

I'm in a bit of predicament in terms of backing up my iMessages. I have 20GB of messages on my iPhone and 20GB on my MacBook (all the same, they're just synced). I have 30GB stored on iCloud. How can I pull everything from iCloud and store it in an External Hard Drive so that I can have all my messages records on a hard drive when I need them. I also want to be able to store the messages on my devices without attachments so that I have the basis of messages but no added junk. I realize I might not make much sense here, but what I'm really asking is whether or not moving my "Messages" folder in the "Library" folder on my Mac to an external hard drive would work for opening again.