Pressure and flow rate from a bowser

In instances like in the video here using a bin as a Bowser, would it be a case of the bigger the bin the bigger the flow rate out the valve at the bottom? Eg would a 120L bin have better flow rate than a 60L using same size ball valve in same location at bottom of bin? And also would it give 1.3 bar of pressure do people reckon coming out of the bin because that is needed also according to the manual of the washer I am looking at.