Assuming you are using the default paper size of 8.5 inches by 11 inches.
The default resolution is 128 pixels per inch.
One thing you can do is to select Set Reduction from the Layout
Menu (or type <Cntrl>%). If you enter 50, you will get a paper
size that *looks* like 17 inches by 22 inches. But when you
print, it will still print on an 8.5 inches by 11 inches paper
because you have not changed the paper size (but just the
reduction/magnification). Since it's still printed on the
original size paper, you can treat this as if you are getting
256 pixels per inch! (Similarly, if you enter 10 instead, you
will be getting effectively 1280 pixels per inch.)
You can also set the reduction/magnification to be larger than
100%. For example, if you enter 200%, the paper size would
look like it's 4.25 inches by 5.5 inches. But it would be
printed on an 8.5 inches by 11 inches papers. Therefore, it's
like everything is blown up 2x. This is good for making posters.
