Of course, if the table is not in a float (a
table environment) and
\partindent is not 0pt (the default) as in this MWE, remember add
\noindent before the
tabular* environment to maintain it between the page margins.
If you refer to extend the table to the page margins, as L. Nielsen suspected, the trick is put the table in a centered box of zero space, and of course, make the table enough big: