Spotlight search to Bluetooth settings hindered by "Bluetooth file exchange"
In Finder open /Applications/Utilities.

Next open System Preferences then choose the Spotlight preferences. Select the Privacy tab.

Now drag Bluetooth File Exchange from Finder to the Spotlight Privacy tab to exclude it from Spotlight (this will work because what is seen as app in by Finder in macOS is actually a folder, although you have to right click it in Finder and Show Package Contents to see it). 



Now try Spotlight again with "blu". 



If any other apps come up before Bluetooth preferences, drag them also into the Spotlight privacy pane.