Why am I not seeing the iOS 13 update?

iOS 13 won’t run on an iPhone 6, it doesn’t have enough RAM and the CPU won’t support it.

Where are you looking?

On iPhone; Settings | General | Software Update

Should come up available for download.

iPhone 6

12.4.2

Are you running a public beta version? Is this for your iPhone?

My phone does not have iOS 13 update either, it says iOS 12 updated

It has updated in my friends iPhone 6

this would imply my phone cannot receive and further updates??

No iPhone 6 or 6 Plus gets iOS 13. Your friend likely has the 6s which does get iOS 13.

You are correct. Maybe there is another bugfix update coming one day, like 12.4.3, but no iOS 13. Your phone is too old and underpowered for iOS 13.

If you want iOS 13 - you need to buy a newer iPhone model. Sorry.

And what model iPhone do you have? And what exact version is it saying.