Q: I dont have wi-fi in my iphone 6s

Take a look at this Apple Support article:

https://support.apple.com/en-us/HT204051

Reset your network settings.

Settings - General - Reset - Reset Network Settings

Reset your device. This won't delete your data stored on the phone.

• Press and hold the Sleep/Wake button
• Press and hold on the Home button
• Keep holding both buttons until the display turns off and back on with Apple logo on it.

Alternatively, you may go to Settings - General - Reset - Reset All Settings

Make a call with Wi-Fi Calling - Apple Support

With Wi-Fi Calling, you can place a phone call if you have a Wi-Fi connection

in an area with little or no cellular ... Place Wi-Fi calls from your iPhone.

support.apple.com/en-us/HT203032

And there are these to consider:

• If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support

To use Wi-Fi Calling, you need an iPhone 5c or later on a supported carrier.

For some other items of similar nature, that may or not be authentic as above:

https://duckduckgo.com/?q=enable+wi-fi+in+iPhone+6s&t=ffsb&ia=web

Hopefully you can convince the iPhone to let you do this.

Tell iPhone it's painless...

Good luck in any event!

edited 2x