Horizontal Rules Between Sections

You can do it with a rich text field or text elements if you get creative. For example I always hide the horizontal lines in section headings and replace with with custom HTML text elements to make my own section headers. If you're on a legacy form you can make something like: 

<p style='border-bottom: 2px solid black; width: 90vw;'></p> and you can create a single line of varying colors or make your own unique section break. You can wrap it under an actual Section Heading element and use form rules to show / hide the section and the text element. 

Newer forms you're out of luck given the way the sections are more like tiles.