Nope, in a low carb plant based diet, most of your calories tend to come from fats with some from protein.
There are plenty of fats in nuts and legumes, which are compatible with a low carb (even if not a zero carb) diet. Seeds are also rich in fats (and are the source of many vegetable oils).
Not a ton of carb calories in lettuce, kale, spinach, broccoli, etc. They’re mostly composed of insoluble fiber (from which ruminants can extract calories but humans can’t) and water.
A “low carb” diet doesn’t exclude high amounts of insoluble fiber. It excludes high amounts of carbohydrate calories.
There are plenty of fats in nuts and legumes, which are compatible with a low carb (even if not a zero carb) diet. Seeds are also rich in fats (and are the source of many vegetable oils).