The autoformat option allows you to format ordinary 'tables' and pivot tables on your worksheets, with pre-defined formats shipped with Excel.  These have a variety of themes, both in colour and black and white. They sense totals in you data and can be changed to a new one by simply changing the selection in the auto format dialog box.

Below we have a fairly plain data table.  In the Auto Format dialog I have selected the 'Colorful 2' format.  This results in the formatting of this table shown at the bottom of the page. Under the options... button you can select to exclude or include various formats, (shown below). You cannot add Formats to the autoformats collection.

Table after application of auto format.t.