Updating your iPhone software (iOS) is a good idea. The update is available for free from Apple. The company applies the latest features and security fixes to the iPhone. Here's how to update your iPhone to the latest iOS version.
Back up iPhone before updating
Although problems during installation are rare, if they do happen, you will most likely lose data.
So, before you install an iOS update on your primary iPhone (or a phone with irreplaceable data), make it a habit to do a backup first.
Update iOS from Settings
Nowadays, most people update their iPhone directly on the device without connecting it to a computer, this is called a wireless installation.
To update your iPhone to the latest iOS, do the following:
Step 1: Open Setting (Settings) on iPhone > select Install elasticg (General) > Software updates (Software Update):
Step 2: iPhone will check for updates. If a new update exists, you will see information about the latest update, including version number and detailed information about the update. If your iPhone hasn't downloaded the update yet, tap Download and install (Download and Install) and enter the password to open the device if required.


Step 3: When the update download is complete, a message may appear asking if you want to install the update now or later. Please press Install now (Install Now), the update will then be verified.
Step 4: Once the verification process is finished, the iPhone will switch to the installation interface with the Apple logo and a small progress bar in the middle of the screen and reboot.

Step 5: Update completed. Enter your iPhone unlock password, agree to Apple's terms again, and start using the new iOS operating system version.

Update iOS in Finder or iTunes
You can also update your iPhone through a wired connection to your Mac or Windows PC. On a Mac running macOS 10.15 or later, open Finder. On a Windows PC or Mac running macOS 10.14 or earlier, open iTunes.
Connect your iPhone to your computer using the Lightning-to-USB cable. If this is your first time connecting iPhone to your computer, tap Trust In the message that appears, ask if you want your iPhone to “trust” the computer.
Locate iPhone on computer. In Finder, you see it on the left under items Locations. Click on it.

In iTunes, find the small iPhone icon in the toolbar near the top, then click it.

In the window that appears with information on your iPhone, navigate to General (in Finder) or Settings > Summary (in iTunes). Click Check for Updates.

If an update is available, click Download, then Update. Enter your password if asked. The update will be installed.
Make sure you have updated your iPhone to the latest version
Once your phone has finished updating, you can check to make sure you've installed all the latest updates.
On iPhone, navigate to Settings > General > Software Update. If your device is fully updated, you will see a screen similar to the one below, indicating that your software is up to date.

Refer to the articles below:
Wish you success!