What happens if I delete "Attachments" folder in my library? Macbook Pro Ventura 12.6.7

You should not manually delete anything in ~/Library, as you could cause all sorts of problems by doing that.

If you need to reduce storage, delete the attachments in the associated messages or emails.

And at least with emails and their attachments you can archive them off to a folder that you can put on an external drive. There are also apps that can archive messages. If you want to pursue that, ask, and people here can recommend good apps.

moe224 wrote:

My messages folder inside ~/Library > Messages > Attachments holds 15 GB on my disk and I want to delete it. My questions is that if I delete it will it delete every single attachment (picture, videos, etc) that I sent on my Macbook Pro Imessage only? Or will it do both, my Macbook and my Iphone? I usually keep videos and pictures on iMessage because I sometimes go back to it in case I remember or need something that was sent in iMessage.

messages are synced through iCloud...