Need help updating my OS

The tags appended to your post suggest that you have an iPhone 5s. Your iPhone cannot be updated beyond iOS 12.5.7.

If you actually have a more recent iPhone capable of update to a more recent version of iOS than is currently installed, the iPhone User Guide provides information on how to update the iPhone:

Update iOS on iPhone - Apple Support

These additional support pages outline both the available methods by which an available update can be performed - and troubleshooting should you experience difficulties:

Update your iPhone, iPad or iPod touch – Apple Support

If you can't update or restore your iPhone, iPad or iPod touch – Apple Support

If your iPhone, iPad or iPod touch won’t update - Apple Support

iOS update and restore errors – Apple Support

Be aware that while an iPhone may be capable of update, in some circumstances you may need to use a computer to perform the update*. To do so, you will need access to either a Windows PC (with iTunes for Windows installed - or the more recent Apple Devices App) or a Mac computer (with iTunes or Finder - as appropriate for the installed version of MacOS). Ensure that your installed version of iTunes has been updated to the most recent version; the essential device drivers are included.

Download and use iTunes for Windows – Apple Support

Update to the latest version of iTunes – Apple Support

Update software on iPhone, iPad or iPod touch in iTunes on PC - Apple Support

Update your iPhone, iPad, or iPod touch with the Finder - Apple Support

Apple Devices App (Windows PC):

https://apps.microsoft.com/detail/9np83lwlpz9k?hl=en-ms&gl=MS

(*) If you don’t have access to a suitable computer of your own, that of a helpful friend or family member will suffice. Alternatively, the technicians at the Genius Bar of your local Apple Store or Apple Authorised Service Provider (AASP) will be delighted to assist.

Genius Bar Reservation and Apple Support Options - Apple

Hello,

There are different ways to ensure the highest iOS that your device will support is installed on your device. When updating, your device will update to the highest version currently available that it will support, or it will just say it is up to date (and can't go any higher) and won't install anything. If you want to run a higher system version than your current device is capable of running, you need to buy a newer device.

Any equipment currently running iOS 12.5.7 can't be updated to anything higher.

An iPhone 5S, 6, or 6plus, will only update to iOS 12.5.7

For future reference:

This support article has instructions about updating an iPhone or iPad wirelessly --> Update your iPhone or iPad - Apple Support Read the article for recommended criteria for being able to use wireless updating.

You can also use Mac and PC computers to update system software --> https://support.apple.com/guide/iphone/update-ios-iph3e504502/ios

Sorry you can’t it was dropped in 2019 and did not get iOS 13 but has gotten security patches but not anymore that iPhone has not been supported for years

Your phone is obsolete. There are no further updates available for it. That model isn't even supported as a basic phone in most of the world any more.

Buy a new on.

The iPhone 5s cannot be updated to iOS 13 or higher. Its hardware is too old and limited.

To run iOS 26, you will need an iPhone 11 through 17 series phone, a 2nd or 3rd generation iPhone SE, or an iPhone Air. Note that iOS 26 is the sixth major update for 11-series phones, so I would not count on them getting any more. It would be better to buy a 16-series phone, a 17-series phone, or an iPhone Air that is likely to receive updates for several years to come.

iPhone models compatible with iOS 26 - Apple Support