I'd love to somehow do the opposite of this but I don't think it's possible? It would be deleting attachments from emails without deleting the email thread.

For example I'm always 1-2 GB away from my Google account being full. I've pruned Google Drive to the absolute bare minimum.

I've had my Google account for a really long time. There's tens of thousands of emails since day 1. However, there's many emails that have attachments.

For example my friends or someone might have sent me a bunch of images and there's a very long email thread going on with them. I want to delete the 300 MB of photos without deleting the email thread. I don't think Google has a way to do this. I'd easily be able to free up multiple gigs of space if this were possible.

I've already bit the bullet and deleted the biggest offenders but I have a ton of emails with 1-2 attachments (pdfs, zip files, some images, etc.) that might "only" be 15 MB but I definitely don't want to delete the email since it has a record of something. Not just the attachment but the corresponding email chain.