Is this what you’re trying to do a kind of perspective template? If so, an alternative way is to do it in Inkscape and save the file so it can be exported to Krita. You only need to take two precautions to make it work: 1) The Inkscape file must not contain any layers; 2) The Inkscape file must be saved in Plain svg format (not normal Inkscape svg).
I made a template for compositions using this method, see here for details.
You mentioned enlarging the page view… it is also possible to resize the canvas by going to Image > Resize Canvas: there you can resize the page in pixels or in percentages, among other options.