Unfortunately, there is no option in Grand Theft Auto Online to gift Shark Cards to anyone. What's more, if you try to purchase it through official means, you'll only be able to do it for yourself and add in-game money to your account, whether it’s on a PC or a console.
Fortunately, there's a way to bypass this, and it is by purchasing GTA Online Shark Card codes.
Shark Card gift cards can be found on third-party retailers like Amazon and Best Buy, and they come in digital or physical forms. Furthermore, the GTA Online Shark Cards can also be purchased on various third party websites that offer codes. However, note that Shark Card prices can often be higher on such marketplaces, but well, we call it a "fee for the possibility of gifting it".
Of course, you can also get Shark Card gift cards for free, although this is not endorsed by Rockstar Games.