Final Draft has several theater templates built in. Go to File > New from Stationery. Select Scripts. You'll see your options for stageplays.
Keep in mind that all Final Draft templates are extremely customizable so if you need different margins, font, etc., you can design your own template.
IMPORTANT: Live technical support (phone, chat, email) for Final Draft 8 will end on December 31, 2017. You will still be able to find information and solutions in this knowledge base, in the online troubleshooter and in the FD8 User Guide.