Open Google Docs in your browser and select a document type. In the menu above the document, select “File”. From the dropdown menu, select “Page setup”. Choose the orientation of the first page by clicking beside “Portrait” or “Landscape”, then clicking “OK”.
In Google Docs, you can create a new document with either the portrait or the landscape layout. You can even take an existing Google Doc and change the page orientation to landscape. What you cannot do is rotate one page in the middle of the document to landscape if the rest of the pages are in the portrait orientation.