Most volume door manufacturers will state on their packaging how much you can cut off the doors. If you cut too much off if can affect the joints and strength of the door so don’t be tempted to cut too much off.
From what I remember you are more likely to be able to cut more off the height (sometimes you can cut more off the bottom) than the width but I think you’ll struggle to find one you can reduce as much as you want.
You could buy one and cut it down and see what it’s like. Remember as well that the style of the door might also dictate how much you can remove before it starts to look a bit odd, especially if panneled or in a particular design. Depending on the interior construction of the door if you cut too much off the width there may not be enough solid wood left to fit a catch.