For anyone trying to this in react. There is a slight difference.
// Document of 8.5 inch width and 11 inch high
new jsPDF('p', 'in', [612, 792]);
or
// Document of 8.5 inch width and 11 inch high
new jsPDF({
orientation: 'p',
unit: 'in',
format: [612, 792]
});
When i tried the @Aidiakapi solution the pages were tiny. For a difference size take size in inches * 72 to get the dimensions you need. For example, i wanted 8.5 so 8.5 * 72 = 612. This is for [email protected].