Auto-resize large images and discard the original to save server space

Even though I am able to use S3 to store images, I still want to greatly reduce the amount of space used. The main problem is that the original image uploaded are often many MB because they come off a high resolution phone or camera.

I have studied and tested many plugins to help with this issue and found that the best and simplest is Imsanity

This plugin creates all the required image sizes and then also replaces the original image file with one resized to a specific size. It keeps the filenames correct so that WP thinks the new resized one is the original file, which it then discards.

I use 1920px max size and in my tests using images off my phone, I can reduce storage space by up to 80%. That's a huge amount of saved space!

I have found this plugin works with WP Media Folder and the Amazon S3 Cloud feature but I'm not sure it will always be reliable. I think it might fail if there were many images or lots of traffic and there wasn't enough time to do the work before the files were moved to Amazon.

And that's why I think it would be best if this functionality were built into WP Media Folder. Then the plugin could properly control everything and do the resizing and removal before transferring to Amazon.

What about the Full resolution files ?
the reason I'm considering the Media Folder plugin is I want the resized/scaled images to be on the WP server and the High Res version to be on Dropbox/cloud

does it do that ??