I can update my phone on latest version

You have to do the update yourself.

What happens when you try?

Can you post a screenshot of the whole screen, it could reveal why you aren't able to update.

Make sure you:

• Are using a WiFi connection (not a hotspot).

• You have an active cell signal

• Have your battery charged at least 50%. Better yet, keep it plugged in during the update.

• Are not using a VPN connection.

• Do not have power save mode turned on.

• Do not have a beta version installed.

• You have at least 6 gigs of storage available.

You can also check out this article for help -

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

https://support.apple.com/en-gb/HT201435

In addition to what Kurtosis12 has provided, if you are unable to update the iPhone, it is possible that you have an iPhone 6, not a 6s. The iPhone 6 cannot update past iOS 12.5.5. If that is what is on your device and when you click on Software Update and it displays that it is up to date, then you have an iPhone 6.

If you have an iPhone 6, you can not update past iOS 12.

Apple isn't here and doesn't read or respond to any post here.

They also can not push an update to your phone.

Update iOS on iPhone - Apple Support