How can I download the iOS using my data

Hello and welcome to Apple Support Communities Loongie,

If we understand your post correctly, you're trying to update your iPhone via cellular data. We’d like to help.

We see you were viewing "Connect to Wi-Fi on your iPhone, iPad, or iPod touch - Apple Support" and it did not answer your question.

You need to be connected to Wi-Fi to download the update:

Update your iPhone or iPad - Apple Support

If you're unable to connect to Wi-Fi try these steps:

If your iPhone or iPad won't connect to a Wi-Fi network - Apple Support

Let us know if that resolves this issue for you.

Thanks for using the Apple Support Communities.