Use reputable third-party retailers like Amazon or Dundle to buy a digital code for the specific country your friend is in. This is often the easiest way to ensure the code matches their region.
Technically, your friend could create a second Apple ID set to your country to redeem the card, but this is a major hassle. They would have to log out of their main account, which stops their current subscriptions and makes updating their existing apps difficult. Gifting - Shopping Help - Apple (AU) buying itunes gift card for someone in another country
Apple Gift Cards can only be redeemed in the country or region of purchase. Use reputable third-party retailers like Amazon or Dundle