If you want to not be tracked I wouldn't even trust airplane mode. With just a SIM pinging towers already a lot can be done. With airplane mode I'm just being paranoid but I never tested radio emissions myself with it disabled so I'd just leave my phone at home if I was really worried about it.
Turning your phone off (airplane mode or power down, which sign out of networks) or lighting up a new one in the same location as an old one was turned off are treated as significant events in these systems and can be configured as an automatic flag for investigation.
If you care, slip it into a faraday bag instead of turning it off or going into airplane mode and you won’t be flagged nearly as likely. People rarely use airplane mode or turn off their phones in situations where it doesn’t provide a useful clue about activity.
There is a huge overlap between surveillance platforms and behavior analysis / data brokers.
