Pro users use audio interfaces. The headphone jack is useful for quick improvised sketching or listening but Apple's official dongle will be fine in those situations as well. It's actually a pretty well made DAC for its size: https://www.kenrockwell.com/apple/lightning-adapter-audio-qu...
For any serious work you'll probably be around a decent audio interface anyway.
It is attached to my studio cans, but that doesn't solve any of the problems I outlined above about varied audio quality between different adapters etc.
For any serious work you'll probably be around a decent audio interface anyway.