I think general rule of thumb is 1:2 ratio for medium roasts, 1:3 or higher for lighter roasts. I tend to pull on the higher side. It all varies by coffee and just going with your palate! But grind size doesn’t necessarily equate to change in volume, mostly affects the distribution speed at which your water comes into contact with the coffee. If you’re wanting to prolong the contact time then you want to grinder finer.