Tucker Carlson on Fox News in February 2018 took two Android phones without SIMs in them, one phone with it set in Airplane mode the other not connected to any network. The reporter then went around Washington DC in a car and by walking. Both phones knew many details when each phone went online (connected to the Internet) it sent a lot of information about the movements of the reporter. It showed where they went to, when they exited the car, where they went to or into while walking and how long they were there.
It is important to note that Chrome on Android, Windows, Mac, and any other platform track you – what sites you visit, what you search for, where you are. Google apps on iPhone like Google Search, Chrome, Google Maps also gather details about you as well that are sent to Google. Any of Googles “free” applications have a associated information loss cost that affect the user of their software and devices. Chrome End User License Agreement – https://www.google.com/chrome/privacy/eula_text.html
Before signing up for a Gmail account, Google Drive or any of the above listed software and services read the details of the software or service agreement. You will see your information is indexed, gathered and it is shared with advertisers and other groups. Google Terms of Service – https://policies.google.com/terms?gl=US&hl=en
Apple on their iPhone devices can gather some details, but it is according to the wording in the software and service agreement only for improving their software and services. It is not at this time sold or used for other purposes according to Tim Cook CEO of Apple, during questioning by Congress in 2018.