How do I update my iPhone to iOS 15?

Bellagee wrote:

Pls I need an updated version

Assuming you have a compatible device, see: Update your iPhone, iPad, or iPod touch - Apple Support

And: If your iPhone, iPad, or iPod touch won't update - Apple Support If the above Apple articles do not help, please post back with relevant information. 

I want to update my iPhone 6s

The iPhone 6s can be updated to iOS 15.8.3

The previous posts in this thread provide you with the instructions for updating the troubleshooting, so we won't repeat them again here.