I would like to illustrate the following: on page 1 of my layout I need the map content on page 2 the legend only and nothing else.
How to proceed?
Layouts are single pages. You'll need to create 2 layouts, one with your map frame and another with your layout. (Each layout will reference the same map).
I assume you're making a PDF because you want 2 or more pages. You'll need to combine the pages together into a single PDF.
There are Python commands you can use to combine multiple PDFs. See the PDFDocument class.