In Google Docs, you can now work with documents that require multiple page orientations. Right-click on the page you want to change and select the option to change orientation. …
Currently a single Google Document can only be either Landscape or Portrait not both. Changing page orientation is done by selecting File and then Page setup… It is currently recommended to separate the Landscape and Portrait pages into different documents. A good place to get more information that might help is at Google Products Forums.
Mix landscape and portrait pages in a single Google doc
How to Change the Orientation on Different Pages in Google Docs
Google Docs Landscape and Portrait
Frequently Asked Questions
How do you insert a new Page in Google Docs?
To add a page in Google Docs on the desktop site, open the "Insert" tab in the menu bar and hover over the "Break" option to find "Page Break." In the Google Docs mobile app, you can add a page by tapping the plus icon at the top of the screen.