Unable to update iOS 16 on my iPhone 6s

rida2312 wrote:

i am unable to download many things … please tell me what should i do.

To run apps that require iOS 16 or higher, you need to purchase a new iPhone, preferably one that is compatible with iOS 18.

iPhone models compatible with iOS 18 - Apple Support

I would suggest narrowing the list to iPhones that support 5G cellular service. I believe that

• The iPhone 12-series through 16-series phones, and the iPhone SE (3rd generation), support 5G.
• The iPhone XR, XS, XS Max, and 11-series phones do not.

You may also want to stick with the newer phones on the list for the simple reason that they are likely to be eligible for future iOS updates for longer. That XR near the start of the list is one of the oldest phones on the list – and one of the two with the smallest amount of RAM. I wouldn't be surprised if, a year from now, it turned out that for it, iOS 18 is the end of the line. For 16-series phones, iOS 18 is just the beginning of the road.

If you are tempted to buy a used iPhone to "save money", please read

The All Too Common SAD Reality of Buying a Used iPad/iPhone – Apple Community

so that you will know what to look for to avoid buying an Activation-Locked and possibly-stolen "brick".

Your iPhone 6S is not compatible with iOS 16 or higher.