Yeah, while those end-of-the-1st round picks do carry a premium value (because of the 5th year option, teams trying to move up to get a QB that slipped, etc.) most likely a trade back nets a 2nd and 3rd. Could also get a 2nd and a 2020 2nd though.
Not sure who either team would want to move up to 31 to get but two teams that would be attractive trade partners are Houston (54th and 55th picks in the 2nd) and Philadelphia (53rd and 57th).
This past April, Baltimore traded with the Eagles for the 32nd overall pick to grab Jackson. The Ravens sent the 52nd and 125th overall picks and a 2019 second-round pick (which is considered roughly equal to a 2018 3rd) to Philly. If you look at those points it's pretty even.
