They have so much money, they can pay every player in the world and they can pay all the salaries as well. Mbappe wouldn't be a problem either, but the problem with very good players and stars is that they have little interest in playing for Newcastle United. Of course, PSG and City also started this way.
If they can make it to the Champions League, I see no reason why world-class players will not sign for them, because their new owners are ready to compete in the Premier League, and they have been trying to bring in world-class players.
Perhaps the richest club in the Premier League right now is Newcastle. But we still don't know how much the Newcastle club owner is willing to spend to strengthen his squad. It is possible that Newcastle's goal is to win the title. And they definitely need talented and star players if they want to win the title. The way Newcastle have been performing this season, it is easy to see that this is a very promising team. They will be playing for both the Champions League and Premier League titles next season. And so now if Newcastle wants to sign a star player, they will probably accept Newcastle's offer.