is there a headphone port on an iphone11

No. There hasn’t been a headphone jack on an iPhone for a few models now. Wired headphones would either need to have a lightening connector or you would need the adapter that allows a headphone jack connector connect to the lightening port.

In addition to the above (correct) info, here’s the (referenced) Lightning to 3.5mm TRRS audio adapter: https://www.apple.com/shop/product/MMX62AM/A/lightning-to-35-mm-headphone-jack-adapter