Still i can update my iphone 6s plus on ios 12.4.7? Thanks

The newest version of iOS avaiable for your iPhone 6s is 15.7.2,

You cannot downgrade to an earlier version if that is what you are asking.

But you can update to 15.7.2 if you have an earlier version.

iOS 15 and iPadOS 15 are compatible with these devices - Apple Support

Still i can update my iphone 6s plus to ios12.4.7?

Check iPhone model & iOS version -> Go to: Settings -> General -> About.

If your iPhone is eligible for an update, you can check by reading this Apple article:

iPhone models compatible with iOS 12 -> iOS 16.

iPhone models compatible with iOS 16 – Apple Support (UK)

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

You need about 6 GB device storage and good Service & Wi-Fi.

If they are On, turn Off Hotspot & VPN.

Charge the battery > 70%.

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, iPad or iPod touch won’t update

If your iPhone, iPad, or iPod touch 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