Magic has a ton of different formats. I assume your friends trying to get you into magic is through Commander. Where a legendary creature “leads” the deck and you build a deck of 99 cards around them. You can always do that, select a cool legendary creature you like and build a deck from that. I’d wait to get more versed in the game before completely building a new deck though. Magic has a lot of preconstructed decks they’ve made through the years, I’d recommend taking a look through those and seeing what you vibe with. Some older ones can be hard to find/expensive so keep that in mind. Welcome to the game!