"Find my iPhone" wasn't activated - and tested - before this phone was stolen. So now any activation, confirmation, or 2FA messages sent to it are going to be intercepted by the thief, lol, not very helpful to the previous owner.
The network carriers and operators can't and won't do anything about this. No text messages, no emails, nothing. The technical capability does exist - every active phone can be located and triangulated with fair accuracy, simply because that's the way cellular radio communications work. If you don't believe it then see how long it takes cops to show up after an urgent-sounding 911 prank. But imagine the reverse situation, where someone (like a thief, hacker, stalker, enemy) is attempting to locate a person through their phone - legal barriers have been installed for good reason.
The only real option for the consumer with a lost/stolen phone is to contact the provider and have the phone registered as a lost/stolen phone. Through Self-Serve on Public Mobile. Blacklisted phones aren't much use to most thieves. Maybe they'll smash it, maybe they'll return it hoping for a ransom or a reward.
My preference is GPS locator tags. In my particular case I've built one into my particular case, "invisibly" sewn and sealed into one of the plastic strap buckle things (along with a couple CR2032 batteries which should be good for years). I don't trust the phone software, it can be broken too easily and it's never fully under my control anyhow. I don't trust the phone hardware, it's not hard to turn it off or to simply remove its battery.
