How do I get the next song to automatically play on my iPhone playlist?

To enable automatic playback of the next song in your iphone playlist, open the Music app and start playing a song. Tap on the "Now Playing" bar at the bottom of the screen, then look for the "Up Next" section. Ensure that the "Repeat" and "Shuffle" buttons are set according to your preference; the next song should play automatically once the current one finishes. If you have a specific playlist selected, the next song will automatically play from that list.