Photos and video in iMessage are filling up my storage! How can I do a mass delete? Can I keep it from happening?

I just learned that media attachments in iMessage is taking up 25 GB of space on my phone. To make matters worse, it's not just stuff people are sending me. If I send a video to three other people, it keeps duplicates for each in iMessage, taking up 4x the storage of the original file. I thought iOS 16 had a way of coordinating this, but I can't figure it out.

I'm trying to clear things up, but there are hundreds of files. It's only allowing me to manually select them one by one, which is taking forever. Is there a way to select and delete all videos or photos attachments at once?

Can I set media attachments to automatically delete after set time period if I don't download them?