When I turn off my phone am I still being tracked?

By having your phone on, your cell phone provider logs your location every minute or so, it varies. “Anonymous” location data is provided to most governments. Unlike popular operating systems, when you put your phone in airplane mode with LineageOS or GrapheneOS it actually disables your cellular radio so it cannot be tracked. 

As another precaution, you can put your phone in a faraday bag for situations when you are worried about being tracked. The normal citizen does not need to worry about this but if you are a high target individual, then I would recommend being minimally connected with a SIM card that is not in your name.