The struggle is real when it comes to constantly needing to make more space on your phone. If it's not photos that are causing problems, it's generally all the music. While any human would probably have a hard time cutting down their collection of tunes, there's a great way that allows your iPhone to do it for you. And there's nothing to worry about - it will only delete songs you haven't listened to in a long time.
To activate this hack, visit Settings > Music and optimize your music storage. Choose the amount of space you'd like to allow for songs and your phone will always keep it under this limit. In order to do this, it will delete songs you haven't listened to for a while. You can always put them back later if you do decide you want to listen again one day.