How to get updates on my phone

It depends on the iPhone and the iOS version you have.

In general:

Go to---> Settings---> General---> Software-update---> Download and install the update.

You must have a stable Wi-Fi connection.

Or connect to a PC with the latest version of iTunes installed.

Charge the battery to 50% or higher.

Turn off Battery saving mode.

Don't use a Hotspot.

Don't use VPN.

And make sure you have enough free space.

What if I have enough space but won’t stay connected to WiFi?

Then you have to connect to a PC, but I already wrote that.......