You need to be more specific. Beef is more expensive to produce than grains. But leafy greens are way more expensive to produce than beef. Non-meat food has a 50x range in cost to produce a calorie. You have to be specific about which non-meat foods you’re replacing meat consumption with. If you’re eating a bunch of kale and avocado instead of meat, then your change probably has no net environmental benefit. If you switch to mostly grains and legumes, then that’s a different story.