Naturally Crossed Eyes
A person whose eyes are crossed outwards, it is mostly likely happening since birth. It is too difficult to cross eyes outwards through practice. While it causes a lot of strain on the eyes muscles, you might be able to achieve only 60 to 70 per cent effect. Also, you might be able to cross your one eye to a full extent while leaving other focused straight. Crossing both eyes outwards is not achievable 100 per cent. Even people who have naturally outward crossed eyes are recommended therapies to get their eyes angle aligned in the center.
Practice or Exercises
You in no way can cross your both eyes outwards unless you have a born condition but later on with practice have managed to align your focus in the center, while being able to leave your eyes to their naturally outward crossed position. Through practice, you might be able to cross your eyes up to 60 or 70 per cent maximum. Yet it is unlikely to achieve the same level of effect in both eyes at the same time. You might be able to cross one eye more and other less, and the only practice or exercise available to do that is looking at two objects far away. It is harder to do and not an effective one as far as achievement of the desired goal is concerned.
Natural Vision Alignment
Natural vision alignment in both eyes focuses the central point. Even it causes a considerable amount of strain on your eyes if you try to focus top of your nose, which is because the eyes muscles control them in the center position. If you practise hard you can achieve an inward alignment also, but only for some time. On the other hand, vision alignment outwards through practice is almost impossible. This is because the muscles' control is as such that it does not allow focus outwards in both eyes and at the same time. You can focus one eye outwards but leaving the other aligned in the center. Even the exercise of looking at two far objects at the same time does not require your eyes turn outwards. Therefore, crossing eyes outwards is very hard. In fact, almost impossible.