This app will open Wi-Fi Display settings if your device support it (or in other words SHORTCUT). Some devices support Wi-Fi Display, but the setting is either hidden or not present. It should also work on Samsung device now. I don't have LG device, so I can't test it.
Only download this if your device support Wi-Fi Display / Miracast, but you can't find how to enable it.
To mirror your screen to TV, you must meet the following condition: 1. Your TV must support Wireless Display / Miracast (check your TV manual) 2. Your TV must be connected to the same WiFi network as your device. You can't connect it with wired connection (LAN). 3. Your Android device must run on Android version 4.2 or newer.