I am preparing a book and wish each chapter title to be arranged in a certain way. Editing styles I see that I can set the font and quite a few other characteristics of the text, but I can not figure out how to actually add things like some carriage returns, or a horizontal rule etc. Can it be done?
You can't add carrige returns as part of a style. You can however set space before or space after the paragraph. You can also add a bottom border to the paragraph to get a horizontal rule.
For both of these to work, the style will need to be a paragraph or a linked style, this won't work on a character style.
Edit the style you wish to use, in the bottom left of that dialog is a format button. If you click that you get a list of options, for space before and after you need to pick paragraph. For the bottom border you need to pick Border.