Q: iOS 10 not available for my iPhone6s Plus

Hello jensen86,
Thank you for using Apple Support Communities. 

I understand from your post that you have not been able to update your iPhone 6s Plus to iOS 10. I know how exciting it is for you to be able to update the iOS on your iPhone. If you are not able to update it by tapping Settings > General > Software Update, then I would suggest using iTunes on your computer to update the iOS. Make sure you create a backup file first if you do not have one already. 

Update the iOS software on your iPhone, iPad, or iPod touch

Update your device using iTunes

If you can’t update wirelessly on your iOS device, you can update manually using iTunes on a computer that you trust. If your computer is using Personal Hotspot on the iOS device that you’re updating, connect your computer to a different Wi-Fi or Ethernet network before you update.

1. Install the latest version of iTunes on your computer.
2. Connect your device to your computer.
3. Open iTunes and select your device.
4. Click Summary, then click Check for Update. 
   
5. Click Download and Update.
6. If asked, enter your passcode.

Best Regards