Selling Vinicius Jr. wouldn't solve the problems, because he's a top-quality player, and Real Madrid would be unlikely to find another player of his caliber. If they wanted to sign him, they'd have to pay a very high transfer fee. Therefore, Xabi Alonso must do his part to the best of his ability and maintain a balance between the players. In this case, the team wins.
Real Madrid has been developing Vinicius for the past few years. Madrid has gradually made Vini experienced. And Madrid will never want to sell Vinicius so quickly. Madrid management always plans for the long term.
I don't think Madrid management has any desire to sell a talented player like Vinicius. Madrid will try to keep him in the squad. Vini is even in Xabi Alonso's match strategy. Now if Vini leaves Madrid, Real Madrid will not be able to find a talented player like Vini so quickly. However, Madrid management does not tolerate injustice. If Vini makes a request that Madrid management does not consider right, then Real Madrid management will definitely decide to sell Vini. Real Madrid management is very experienced and they make decisions independently. I have not seen in the past that a player has been able to influence Madrid management.