Welcome to Android Central! If someone reset it, and assuming it's on Lollipop or higher, the thief won't be able to get to the Setup Wizard again, because the phone will prompt them to enter your Google name and password. This is Factory Reset Protection. Since there would be no way to turn on the network, then I don't think you'd be able to locate it (but at least you know that your data is safe, and your phone can't be used).
To be even safer, though, make sure you change your Google account now, and report your phone as stolen to your carrier and to the police.