The question is just the cost of Mbappe on the transfer market and will Real Madrid be ready to spend hundred of dollar to buy him when he only has one more year in the contract. I believe that Real Madrid have enough patience to wait one more year and save a lot of money.
Waiting is not Real Madrid's type, they will do anything to get the player they want. PSG will accept proposals from any club if Mbappe does not want to extend his contract, PSG has full rights to sell Mbappe to any club as long as Mbappe's contract is still active. Real Madrid will not stand still until the player they want has been brought in, the price is not a big problem for Real Madrid, especially since they have included Mbappe on the radar for the last two years. The loss of Benzema made Real Madrid urgently need to bring in a new striker, Mbappe is the right person to fill the post left by Benzema.
Kylian Mbappe's situation is similar to Ronaldo's when he moved from Man United. Clubs cannot hold players who no longer wish to be at the club. PSG should focus on using their money to build a reputation to make it easier to attract other star players. Now the only club that currently can afford Mbappe and needs him is Real Madrid.
Because I think Real Madrid is the only right club for mbappe. Benzema left Real Madrid for the Saudi Arabian league and the number 9 is still open for Mbappe. Using the number 9 in real madrid I think this is the best choice for Mbappe, hopefully he realizes that.