Set edge Cache-Control with Response Header Modification Rules

I want to setup a Response Header Modification rule that checks if a edge cache control header (s-maxage) is set, and if not, add it.

It’s rewriting the header just fine, but the edge-cache doesn’t HIT (always EXPIRED), so I’m guessing the headers are set after Cloudflare does it’s cache thing, is that correct?

Origin Cache Control and Cache Everything is enabled through a page rule

Is it possible to modify edge Cache-Control with Response Header Modifications?