Reached from base.pdf's overflow menu on Project Files. Generates a blank page at a chosen size/color and overwrites the current base.pdf - handy for starting from scratch or resetting the canvas, or replacing it with your own externally-designed file by copying over it directly instead.

This only applies when the project uses a physical base PDF (see Project Properties); overwriting is destructive to the old file and can't be undone.

Existing blocks in your layout keep their exact position/size - if the new page size differs from the old one, everything will look shifted relative to the new canvas, so re-check block positions afterward in the Layout Editor.