At any time, you can check for software updates and install them. The screen shows the version of iOS currently installed and if there are any updates available. Every time Apple releases a new update, it introduces new features, bug fixes, security patches, and other optimizations. Therefore, updating your iPhone will make it faster and safer.
That's one of the reasons why you should update your iPhone regularly. Here's how to update your iPhone manually and automatically, and what to do when your iPhone isn't updating properly. The latest iOS software update, iOS 15, is available for iPhone 6S and later, as well as for the iPhone SE (first and second generation) and the seventh-generation iPod Touch. iOS 15 will take up about 3.24 GB of storage space, but you'll need more than that to successfully install the update.
In fact, you'll need a total of about 5 GB of free space on your phone to download and install the update.