Below shows what my homepage currently looks like. I have an image banner, which includes the Title, Subheading and button. However, I need to include one more line of text (shown by the red arrow below) - and I am not sure what the best process for this is?
Add a Text/Rich text block inside your hero section in Themes → Customize, most themes allow this right under the main heading. If yours doesn’t, drop a simple <p> in the hero section’s Liquid file and style it with a small top margin.
If you’re open to editing theme code, then remove this line.
This will allow you to add several “Text” blocks to this section – more lines of text.