Reboot Remotely any Iphone Mobile Phone with a Simple Text Message / Viber Message or WhatsApp message

effective.
Power
لُلُصّبُلُلصّبُررً ॣ ॣh ॣ ॣ
冗

This is working on virtually all IPhones though I’ve seen reports the bug doesn’t affect IPhone 4.
The reboot bug is caused by iMessage

When an incoming message is displayed through Apple’s built-in banner alert notification system, or even directly on the lock screen if the device is locked, iOS makes an attempt to abbreviate the scripted message with an ellipsis as is standard when trying to shorten text in a container that isn’t big enough to display the whole string. However, it appears that if the ellipsis is placed in the middle of non-Latin script characters, such as Arabic or Chinese, it causes an internal error and forces the system to crash and reboot every time.
Because of the very specific nature of the text string that is actually required to be received by the device before a crash will occur, it’s highly unlikely that this will happen purely as an accident. With that said, there are a number of workarounds to resolve a rebooting device if the problem does occur. If the Messages app is reopened directly to the offending conversation then simply sending a reply to the message will resolve the issue. Alternatively, users can also utilize Siri to send a text message or a photo from Photos app Share Sheet to the sender to resolve the issue.

Meanwhile jailbroken users can install this .deb file using iFile to fix the issue.