TOC 1, TOC 2, TOC 3, etc., are built-in styles that you cannot delete or overwrite. You
can modify them. Those are the styles that are applied to various levels in the TOC. They have nothing to do with formatting of text in the body of the document.
Generally, the easy way to modify one of these TOC # styles is to just change the paragraph formatting for one entry in your TOC and OK your way back.
By default, the style will update. For styles with numbering or bullets, you change the indents by using the define new multilevel list dialog.
Usually one does not generate styles instead applies them. You can create or modify a style.