How to turn on Instagram dark mode for Android and iOS

Not forgetting why all top brand is adding dark mode to their apps; to make it easier for the user to operate at night. From changing your background color scheme to a black; you presume to be saving your battery. YouTube, Slack, Twitter, Evernote, Google Keep, and Gmail all have dark mode—and Instagram is not let out, because you can now enable dark mode for Instagram on your smartphone.