Facebook rolled out dark mode for Messenger on mobile to a wider set of users earlier last month, although there was an easter egg to enable it. At the time, people had to send a crescent moon emoji to one of their friends before the dark mode option appeared in the settings.
Today, Facebook announced that it is letting anyone across the world switch on Messenger's dark mode without having to go through that rather bizarre way. The dark mode toggle is readily available on the settings menu on Messenger for Android and iOS from today. To access that option, just tap your profile photo on the top left corner of Messenger and you will see the settings where the dark mode option appears at the top.
It is worth noting that there's no change to the dark user interface of Messenger with this new update, except that the process has become easier and more straightforward this time. It is still the same true black, conducive for when you want to chat with friends at night time or simply wish to use that feature all the time.