You can convert your calendar screens to a PDF file.
Open the calendar screen you want to save. Tap on the share (arrow) button in the top right of the screen.
In the "Convert to PDF" screen, you can tap on the "Page Layout" button to change layout options, such as single page, paper size and date range.
Tap on the "Save" to save the PDF file to a cloud server or local files area or to backup your calendar.
You can also tap on the 'Email' button to send the PDF file via email.