i can;t update my iphone 4s

Does it provide any hints as to why you can't?

Realize that a 4S can only update as far as 9.3.6.

If your device won't update, make sure you are following all the conditions for the method you are trying to use. If you are sure you are following directions correctly, try a different method.:

Update your iPhone or iPad - Apple Support - wirelessly*

Update iOS on iPhone - Apple Support - with a computer for an iPhone, or a related computer one for an iPad Update iPadOS - Apple Support

If your Apple mobile device won't update, read this support article for a list of possible reasons --> If your iPhone or iPad won't update - Apple Support

Another, less common reason for not being able to update is if you were using a beta version of software. Refer to How to uninstall iOS or iPadOS beta software - Apple Support

If you need more space for an iOS update read this support article --> If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

If your update feature on a device is greyed out or restricted, it may have been disabled using Screen Time, or by an IT administrator if you are using a device owned by an employer or educational institution. Read this document about using Screen Time on an iPhone, iPad, or iPod touch --> Use Screen Time on your iPhone, iPad, or iPod touch - Apple Support

Tap Settings > Screen Time > Content & Privacy > scroll to Allow Changes.

* From ASC contributor Lawrence Finch at https://discussions.apple.com/thread/254821361?answerId=258984965022#258984965022 here's a checklist of criteria that all should be met in order to update wirelessly:

• You need at least 10 GB of free storage for iOS 16 or 6 GB for iOS 15 or lower; more is better

• You must be connected to a Wi-Fi network (and not a personal hotspot)

• The phone must be charged to at least 50%, and preferably plugged in so it stays above 50% during the update

• The phone must not be in Low Power Mode

• The phone must not be connected through VPN, and it may be necessary to delete any VPN apps and VPN profiles

• The phone cannot be in Airplane mode and must have a cellular data connection

• You cannot still have a beta version installed on the phone

• You cannot have a previous version that was downloaded, but not installed - go to Settings/General/iPhone Storage to look; if you find an iOS installer, delete it.