why is charging port in my iphone 6s is not working as a head set jack

Hi

The iPhone 6s has a 3.5 jack socket for headphones.

It,s iPhone 7 & above that the lighting port works with headphones.

Cheers

Brian 🇬-1F1E7;

Both answers above this one are wrong.

The Lightning (charging) port on an iPhone 6s and in fact the lightning port on any iPhone or iPad with it, works as a headphone jack perfectly fine. The only requirement is that the device must be running iOS 10 or later for it to work, as explained in the support document you came from:

Use Apple headphones with your iPhone, iPad, and iPod - Apple Support

To use Apple EarPods with Lightning Connector, you need an iPhone, iPad, or iPod touch that has a Lightning connector and iOS 10 or later.

There is no device model limitation. It is intended to work that way on all devices with that type of port.

If yours is not working, there is something wrong.

What happens when you plug in the headphones into the Lightning port?

Are you using Apple Earpods? Or 3rd part headphones?

Do the headphones you are using work on a different device?

just because the connection fits, does not make the feature work, the internals of the phone are different since it has the headphone jack.