Hello Everyone, It's an issue only with Flex. Because that sensor is on only the part who detects the Flip cover and if sensor is not on flex then obvious On/off Function will not shown up on the screen in settings.
It's work like if Your Computer has wificard or any other device then it's only shown at Device manager because computer knows that There is a device attached to me if not then computer not gona show anything.
Same as there if sensor is there then it's shown otherwise you have to Decompressed or Short a Sensory memory Supply. So system will Show on/off button
Thanks. This is genuine Way and easiest. If you find other please Share.