I want update my iPhone to 14.1

It is unclear what model you have.

•If you have a 6S as shown in your stats, you can update to iOS 15.7.9

•If you have a 6 as I suspect since your stats also show you are on iOS 12, then an iPhone 6/6 plus can't be updated beyond 12.5.7, it doesn't have the hardware needed to run anything higher. If you need a higher iOS version, you will have to purchase a newer phone.

To update to 12.5.7 -

Go to Settings > General > Software Update.

This link will show you how to update your iPhone, iPad, or iPod touch using WiFi -

Update your iPhone or iPad - Apple Support

This link will show you how to update using your computer -

Update iOS on iPhone - Apple Support

iPhone 6s, iOS 12

If it is an iPhone 6S you can update to iOS 15.7.9, see -> iPhone models compatible with iOS 12 -> iOS 16.

iPhone models compatible with iOS 15.5 – Apple Support (UK)

You need about 8 GB device storage and good Service and/or Wi-Fi.

If they are On, turn Off Hotspot & VPN.

Charge the battery > 70%.

Go to Settings -> General -> Software Update -> Download and Install.

See the following Apple articles:

Update your iPhone, iPad, or iPod touch

Update your iPhone, iPad, or iPod touch - Apple Support (IN)

If your iPhone or iPad won't update

If your iPhone or iPad won't update - Apple Support 

You can do the update via PC, see this Apple article: Update software on iPhone, iPad or iPod touch in iTunes on PC

Update software on iPhone, iPad or iPod touch in iTunes on PC – Apple Support (UK)

If you have a Mac see this Apple article: Update your iPhone, iPad, or iPod touch with the Finder

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

or see:

If you have an iPhone 6s, you can upgrade to the most recent version of iOS 15. (Apple no longer offers iOS 14 as an upgrade when coming from iOS 13 or earlier.)

Update your iPhone or iPad - Apple Support

If you have an iPhone 6 (no "s"), iOS 12 is the highest major version of iOS that it can run.