To optimise *before* sending to S3

Love this plugin. As asked in another thread, I am using the WP Offload S3 plugin to send all images to an S3 bucket, so I can keep my own hosting costs down. The media path is a CNAME of the cloudfront that sits in front of this S3 bucket. All this works.

What I’m not sure about is whether EWWW works *before* the file is thus sent to S3? How can I ensure that to happen, without any custom code or hacks in my themes file?

Thank you.

https://www.ads-software.com/plugins/ewww-image-optimizer/