How to see  data in iOS logs?
There is no single setting that you can change for iOS logging as there is for macOS.

If you are running a beta version of iOS, the private log information seems to be collected, so that is one option.

The other option is to see if there is a profile on this page that covers the logging you need.

Once you install the relevant profile you will see the previously &lt;private&gt; information appearing in the iOS console log.  

In my case I was able to use the "Baseband" profile to enable caller id logging while working on a CallKit extension. 

To disable the private logging you simply remove the profile from general settings on the device.