The Dallas Cowboys have not traded down in the first round of an NFL Draft in quite some time. It was 2021 when Dallas last moved backwards in the first round of the draft, and doing so proved to be a wise thing as the Cowboys ultimately were able to still land Micah Parsons. Even then the previous trade-back instance worked out wonderfully in 2013 as it led to Travis Frederick.
In both of those instances the Cowboys picked up extra draft capital while moving backwards and still landed players that they really liked.