I wonder why you would want it?
Honestly I ran eco mode for 6+ months on my 2.7 BaseSquatch, when I went back to Normal mode didn't see a difference in mileage. So it did nothing for me.
I was surprised as well when I read that. With larger tires and a larger engine, Eco mode would have been nice. It helps save gas on acceleration as well as cruise control recovery.
I think my biggest surprise was at the price of a Raptor, I'd damn well be getting every GOAT mode there is but they are missing anothe mode besides Eco so you are getting shortchanged by 2.
Panda has a dash conversation kit to install a Raptor Dash in a normal bronco and they explicitly state the dash will not display those 2 modes even if your Bronco has them on the dial.
I have tried ECO mode on a few different vehicles driving with a very light foot. In every case I got about 2 MPG less that with normal driving mode. Never will try it again.