Draw page size much smaller than paper size

I have just created a new draw document. In Tools->Page Properties, the page size is Letter. All margins are 0.4".

The maximum area I am allowed to draw in is 1.54"x2.04" This is much, much smaller than a sheet of Letter paper. It’s smaller than an index card.

How can I use the full area of the page?

Here’s the file in question: Dropbox - Stroke Gauge.odg - Simplify your life

Could you provide that empty document to experiment with (using some file sharing service like filebin.ca)?

Added to OP. I’d hoped that there was just a simple feature I was missing.

Options-LibreOffice Draw-General-Scale