Yes, you can turn on Find my phone remotely if it's turned off. To do this, you'll need to use the Find My iPhone feature in iCloud. This will allow you to locate your device and take action even if it's not turned on or connected to a network. Here's how to turn on Find my phone remotely:
1. Log into iCloud.com with your Apple ID and password.
2. Click on the Find iPhone icon.
3. Click on the All Devices drop-down menu and select your device.
4. Click on the Actions menu and select Enable Lost Mode.
5. Enter a phone number where you can be reached and a message that will be displayed on your screen when someone find s your device.
6. Click on the Done button when finished.
Now, whenever your device is lost or stolen, you can log into iCloud and activate Lost Mode which will lock down your device and display a custom message with your contact information. Anyone who finds or has your device will hopefully see the message and reach out to you so you can get it back!