It seems that Real Madrid are watching Bayern Munich's left-back. He is Alphonso Davies, 23 years old. His contract with Bayern Muchen expires this year, so they don't want to repeat the mistake of Kroos' move. Kroos moved on a free transfer. Munchen does not want Alphonso Davies to move on a free transfer and perhaps this will make Bayern Munich have to let him go this summer.
Real Madrid actually has 2 left-back (Mendy and Fran Garcia), they don't really need new left-backs. Real Madrid is watching Davies because he has a chance to leave Bayern Munich with a free transfer status. Since Davies is a top left-back, Real Madrid don't want to miss the chance to sign him for free. However, if Bayern Munich extends Davies's contract, I'm sure Real Madrid will prefer to stop watching him.
Real Madrid should focus on looking for a new center-back and right-back. In these positions, some players are more than 30 years old (all Real Madrid left-backs are 32 years old). Real Madrid need to plan to sign new players with young ages to replace the current players. Reece James, Alexander-Arnold, and Achraf Hakimi are good candidates for the next Real Madrid right-back.
In terms of players, it seems that for left-backs until now it is enough because Fran Garcia and Mendy, even though their age is still young but they have quite a lot of experience, besides that there is also Camavinga who is ready to be positioned there if there are obstacles to this player, it's just that maybe in this case Madrid wants to make Davies a target because from the previous few seasons Mendy's rumors of leaving Madrid have always surfaced so they started trying to anticipate this.
As for the right-back, their two pillars, Vazques and Carvajal, are both 32 years old. Even though it is old age, they are still very capable of being there and instead of focusing on the 2 wing-backs I think it would be better for them to focus on the center-back. Even though until now their players are qualified there because they are filled with Rudiger, Militao and Alaba but when injury problems occur like what is happening now, it becomes a problem for them even though there are Nacho and Tchouameni who can still cover but in the end getting players who fit their position will be much better.