A family of Microsoft word processing software products for creating web, email, and print documents.
First select the part that should be landscape. Then click the little arrow in the bottom right corner of the Page Setup group on the Layout ribbon, to open the Page Setup dialog box. Make sure that the "Apply to" box says "Selected text", click the Landscape button, and click OK.
Word will insert Next Page section breaks before and after the selected text, and it will set the page(s) between the breaks to landscape orientation.
If you use a header or footer in this document, and a page number or other text is aligned at the right margin, you'll need to insert an "alignment tab" to make that right aligned text go to the margin of the much wider landscape page. See https://www.techrepublic.com/blog/microsoft-office/use-word-2007s-new-alignment-tab-feature-to-align-text-with-margins/ for instructions.