Opt in doesn't necessarily mean hidden in settings. For this feature it probably should be a pop up that appears the first time each user enters a search reques

Opt in doesn't necessarily mean hidden in settings. For this feature it probably should be a pop up that appears the first time each user enters a search request before it gets sent over the network. The question could have a positive spin "Would you like to see network enhanced search results?" with details and privacy policy links. Options of "Yes", "Ask later" and "Disable enhanced search". They could even put an "Are you sure?" If disable is selected.