My phone will not update

1. Make sure you have a good WiFi connection.
2. If you are using a VPN turn it off.
3. You need to have 6 GB of free storage space on your iPhone.
4. Make sure you have a 50% battery charge and preferably connected to power
5. Turn off Low Power mode

If this doesn't work go to Settings > General > VPN & Device Management and remove the beta profile if you have one.

And if all that doesn't work update your iPhone via your computer.

It’s fake update

Given how far behind you are in updates you should update via your computer.