You can control general settings like Bluetooth, WiFi, and Airplane mode by hopping into the Settings app on your iPhone or iPad, or through Control Center. But why if you can just ask Siri to enable or disable a setting for you? Here's how:
How to toggle general iPhone and iPad setting with Siri and iOS 7
Launch Siri by pressing down and holding the Home button on your iPhone or iPad running iOS 7 or higher.
Say something like Disable WiFi or Turn on Airplane Mode.
Wait for Siri to understand what you said and disable or enable the setting in question.
That's all there is to it! Currently you can ask Siri to control Airplane Mode, Do Not Disturb, WiFi, Bluetooth, Rotation Lock, screen brightness, and volume. You can also of course ask Siri to launch any app you have installed too.