The latest generation of iPhones (the 11 and 11 Pro) contain the new U1 chip, which lets your iPhone locate other iPhones with pinpoint accuracy. Currently it is only used to show you the direction of other iPhones when you AirDrop a file. However, it will almost certainly soon be used to keep track of the rumored Apple Tags (or AirTags) tracking devices.
But what if you want to turn off UWB (ultra-wideband) tracking altogether? No problem.