Hi. I come with 2 problem solved answers. (Note: for online PDF Files without printing).First and quickest solution:On your Google Document, click File - Page Setup - and by the Paper Size, choose “Folio 21,6 cm x 33.0 cm”. And thats it. Stretch your pic to fill the page and once you’ve downloaded it as a PDF file, you will see your File with the pic filled entirely.Top and bottom margin must be set to zero. You can add your footnotes/headnotes without worries. It is a tiny bit different than the regular A4 (21x29,7cm) size paper but you won’t notice that (unless you wanna print it).Second solution, a bit longer:Create two files,Save your wished-stretched-titlecover-picture (only) as a Google Slide presentation and save it as a PDF. Steps:1. Click File on your Google Slide Sheet - Page Setup - Click Customs - type in 21.0 cm x 29,7cm and press OK - click on the Menu “Background” and add your picture, it will automatically filled it to the entire page. Save as PDF.On your Google Doc, simply save your work (text etc) aswell as PDF without “that front page picture”.Once you have done both, save/combine these two pdf files in one. www online2pdf if you dont have a program.Hope this helped.Rayhanah.P.S. If youre looking for a solution to print this, perhaps you might have to setup your margins by the print settings