Step 1: Turn on your Mac and then make sure that the Mac is up-to-date. The following simple steps show you how to do it: Update Your iPhone via Finder

Updating your device via iTunes or Finder is very easy. How Do I Update iOS with Finder and iTunes?

Mac users who still run macOS Mojave and lower as well as PC users can continue to use iTunes. Therefore, Finder will be useful to macOS Catalina users to sync content like music, movies, tv shows, books, photos, and other files. When you connect the iPhone to the Mac and then open Finder, you should be able to find all the familiar features that you would use to manage the iPhone in Finder. But this doesn’t mean that you will not be able to manage your device the way that you used to with iTunes. With the introduction of macOS Catalina, Apple replaced iTunes with other apps like Music, TV and Podcasts. For example, when your device’s battery doesn’t hold charge like it used to, updating via iTunes may prove easier and more effective. You may also want to update the device via iTunes when the device has software problems.While the full build that you get when you update via iTunes or Finder full replaces all the code of the previous iOS. Delta updates are often smaller files and will change only the section of code that has changed from the previous version. When you update your device via iTunes, you get the full build of iOS firmware rather than the delta updates that you get when you update OTA.There are several reasons why you would want to update your device through iTunes rather than OTA. Whatever the reason you are choosing to update your device via iTunes, the following guide will prove very helpful.

It can sometimes become necessary to update your iPhone via iTunes when an OTA update is impossible, particularly when the device is experiencing software issues. In this guide, we take a look at how you can update your iPhone through iTunes.

Update to the latest version of itunes