turn off Find My iPhone
How do I turn off Find My iPhone when the phone no longer turns on? I do have the replacement phone.
iPhone 5s, iOS 12
What if your device is off or offline?
If your missing device is off or offline, you can still put it in Lost Mode, lock it, or remotely erase it. The next time your device is online, these actions will take effect. If you remove the device from your account while it's offline, any pending actions for the device are canceled.
https://support.apple.com/en-us/HT201472