How to put a landscape page in a portrait document
You you should change the webpage subject Portrait and landscape in one document The portrait page after the landscape page is upside down.
Changing Page Orientation (Landscape or Portrait) of the pages in a document. Page styles 3.4/Writer/Changing_Page_Orientation_Landscape_or_Portrait
PowerPoint itself does not allow you to have both portrait and landscape slides You’d have to rearrange the page order in PowerPoint How to Put Pictures
Mirrored Margins with Landscape Sections. If you have a document with both landscape and portrait See How to Put a Portrait Page Number on a Landscape