Hello,
When a new DOCX is created using CreateDocx, default page size and margins are added. The default paper size is set in config/phpdocxconfig.ini :
; default paper size
paper_size = "A4"
You can customize the default paper size changing this value. Using the modifyPageLayout method the paper size, the margins and other settings can be changed. When adding new sections with addSection, the paper size and margins can also be set.
Or you can use a custom DOCX template with CreateDocxFromTemplate.
Regards.