The answer to this question is both yes and no. Harry Potter can use Lumos outside Hogwarts, but it is much more difficult to do so. Lumos is a spell, and any witch or wizard is able to use it. However, it is much easier to use the spell within Hogwarts, because the school is filled with magical energy. Outside of Hogwarts, the magical energy is much less concentrated, and it can be more difficult to use the spell.
The energy necessary to use Lumos is the same inside and outside Hogwarts. However, the magical energy outside of the school is not as concentrated, so it takes more energy to use the spell. Additionally, it may require more skill to cast the spell outside of Hogwarts. With more magical energy concentrated in one area, it is easier to conjure the spell, and the spell is more likely to work.
In order to use Lumos outside of Hogwarts, Harry must be able to focus his energy and direct it to the necessary area. This is not an easy task, especially for someone who is inexperienced in spell casting. He must also be able to focus his intent and know exactly what he wants to achieve. If Harry does not have the necessary skill or focus, then the spell may not work.
Using Lumos outside of Hogwarts is not impossible, but it can be challenging. It requires a great deal of skill and focus, and it takes more energy to cast the spell. For a beginner witch or wizard, it may be best to practice the spell within Hogwarts before attempting it outside the school.
Harry Potter has the same ability to cast Lumos inside and outside of Hogwarts. However, the concentration of magical energy is much less outside of the school, which can make it more difficult to cast the spell. It takes more skill, energy, and focus to use Lumos outside of Hogwarts, which is why it is recommended to practice the spell within the school before attempting it outside.
For Harry Potter to use Lumos outside Hogwarts, he must be able to focus his energy and intent, and he must have the necessary skill in order for the spell to work. It is possible to use the spell outside of Hogwarts, but it requires more energy and skill than it does within the school.