Friends Not FoeTranslation: Perform the 'Pirate Salute' gesture to befriend someone in-gameThere is a "Make Friends" emote that you can do, and if both players do this emote towards each other, then you become friends on Xbox. According to
NafrayuNox you can even already be Xbox friends, just as long as you do the emote, you should unlock the achievement.
So while also going for
The I'll Drink To That achievement in Sea of Thieves worth 14 pointsTwo different crews, their tankards held high, will meet at a tavern and drain them all dry! you could drink the grog while the other crew is around, then do the make friends emote.