I believe you are talking about what I call form punctuation. This is similar to form of concrete poetry but instead of the entire poem taking on the form of the subject, varying the form of the structure at strategic places enhances the impact of a particular word of line. This is most commonly done by isolating the word or line in a verse with space above and below, but can also be done by "indenting" the start of a line. I like to use this type punctuation in descriptive free verse, but alas the site doesn't presently allow such without double spacing lines which dilutes impact. Visual presentation can actually place limited imagery directly on the page