These built-in styles are provided as samples of what can be done in Writer.
Body Text is the “reference” style for all which are used in your main topic (excluding headings, captions, notes, headers, footers and TOC). All main topic styles will initially inherit their attributes from Body Text.
Body Text itself inherits from Default Paragraph Style, adding some spacing and changing line spacing. By default, you get something like this:
+ <== left margin right margin ==> +
|Lorem ipsumdolor sit amet, |
|consectetur adipiscing elit. |
Body Text, Indented adds a left indent to Body Text:
+ <== left margin right margin ==> +
| Lorem ipsumdolor sit amet, |
| consectetur adipiscing elit. |
First Line Indent also inherits from Body Text but changes only the first line:
+ <== left margin right margin ==> +
| Lorem ipsumdolor sit amet, |
|consectetur adipiscing elit. |
You also have Hanging Indent which plays both on left indent and first line to create the following effect:
+ <== left margin right margin ==> +
| Lorem ipsumdolor sit amet, |
| consectetur adipiscing elit.|
All these layouts can be customised to your needs, but try not to break the idea conveyed by the name.
What I mainly do is to balance vertical spacing between above and below paragraph. IMHO, setting only below paragraph as is done in the factory configuration is not ideal when you mix styles, e.g. heading and main discourse, because it does not fully take into consideration the semantics of adjacent styles, causing too many manual adjustments (hence dreaded direct formatting).