My iPhone can’t update the new iOS version

Click on this link to read how to "Update your iPhone, iPad, or iPod touch" --> https://support.apple.com/HT204204 - When you try to update you will only be given one update selection which will be the highest available iOS version supported by your device. If it says the device is up to date and you need a higher OS version you will have to buy newer equipment.

Given that you have not identified what version of iPhone you currently have, or what version of iOS, it is difficult to answer that question. You may not be able to update your device as Limnos has indicated, or it could be some other issue as stedman1 provided. If you still do not understand, provide the model of iPhone you have and what version of iOS.

Read through the user tip below.

Updating iOS: common issues and solutions - Apple Community