How to change the size of a text field in unity built-in Button component Inspector view?

I have got unity’s built in UI component called Button. I have it call a method that takes in a very long text as an argument.

The problem is, when I start typing this long text into the input field of the component, it reaches out of the boundaries and is really hard to manage.

How to change the size of text fields in Button components editor.
I think I would need to change the source code of this component to have bigger text fields, but can’t figure out where and what to change.