Hello Irene. Here's an easy way to change the size of a Drunkard's Path block.
Measure the length from the corner of the block within the quarter circle to the edge of the circle (the radius). Divide that number by the total length of the block. Now multiply that result by the length of the block you want to make. This will give you the length of the circle part for the new block.
For example, if you want to make a 9 inch block and you have a 6 inch block with a circle part of 4 inches, your math would be 4 ÷ 6 x 9 = 6. The circle size for the 9 inch block would be 6 inches. The proportion is usually about two thirds circle, one third arch.
Hope this helps.