Stolen phone Find my iphone not enabled

If you did have FindMy enabled. It will show up on iCloud.com under the find section. You will see it in the device list. Below is a personal example. If that is the case, then yes. Your device will erase if it connects to the internet.

But if it FMI was not enabled. It will not. The following is what apple recommends for device that are lost, and FMI was not turned on. I also attached the link for more details

If Find My iPhone or Find My iPad isn't enabled on your missing device

If your missing device doesn't appear in the Find My app or at iCloud.com/find, you didn't turn on Find My. There's no other Apple service that can find, track, or flag your device for you. But there are steps that you can take to help protect your data.

Change your Apple ID password

If you use more than one Apple ID, you should change the password for each Apple ID that you have.

Change your Apple ID password.

Change your password for other accounts

Change the passwords for other internet accounts on your device, like email accounts, Facebook, and Twitter.

Report your missing device to local law enforcement

Law enforcement might request the serial number of your device.

Find the serial number.

Contact your wireless carrier

If the missing device is an iPhone or an iPad with cellular, report your missing device to your wireless carrier. Ask the carrier to disable your account to prevent calls, texts, and data use. And if your device is covered under your wireless carrier plan, file a claim.

Remove your missing device from your list of trusted devices

Go to appleid.apple.com to remove the missing device from your list of trusted devices.

https://support.apple.com/en-us/HT211207

Look for your device on a map

To find your device, sign in to iCloud.com/find. Or use the Find My app on another Apple device that you own.

If your iPhone, iPad, or iPod touch doesn’t appear in the list of devices, Find My was not turned on. But you can still protect your account if Find My was not turned on.

Mark as Lost

When you mark your device as lost, you remotely lock it with a passcode, keeping your information secure. This also disables Apple Pay on the missing device. And you can display a custom message with your contact information on the missing device. 

Mark your device as lost.

Report your missing device to local law enforcement

Law enforcement might request the serial number of your device. 

Find the serial number.

File a Theft and Loss claim

If your missing iPhone is covered by AppleCare+ with Theft and Loss, file a claim for an iPhone replacement.

File a claim.

Remotely erase your device

After you erase a device, you can't track its location, so make sure that you no longer need to search for the device. If you have AppleCare+ with Theft and Loss, do not erase your iPhone until your claim has been approved.

Erase your device.

Contact your wireless carrier

If the missing device is an iPhone or an iPad with cellular, report your missing device to your wireless carrier. Ask the carrier to disable your account to prevent calls, texts, and data use. And if your device is covered under your wireless carrier plan, file a claim.

Remove your missing device from your account

If you have AppleCare+ with Theft and Loss, do not remove your lost iPhone from your account until your claim has been approved.

Go to appleid.apple.com to remove the missing device from your list of trusted devices.

I need to track my iphone