After the international break, there will definitely be differences in the team and indeed Real Madrid are currently in their best performance, but that doesn't guarantee that they will remain like that during El Clasicco, as we know, matches between two of La Liga's top teams always present tough battles. fierce with high tension so I think anything is possible to happen and this is difficult to predict.
Despite the problems and player crises due to injuries that are currently affecting the Barcelona team, I still believe that Xavi will still be able to maintain the stability of the Barcelona team.
Two big clubs like Real Madrid and Barcelona will always be fierce competition at the end of the season but they both have differences, as we already know, Real Madrid is more concerned with the Champions league match with good financial conditions, so Real madrid is always more ambitious in chasing title in the league. champion, while Barca currently has a financial crisis, they are only able to fight consistently in every match in the champions league, even though there are a few difficulties, but what is more certain is that Xavi not want to waste the opportunity when his rival club is focused on other competitions Barca will continue to improve its points in LaLiga to provide a distance of points which is quite far from other club.
Furthermore, I agree with you that after the international break there will be a lot changes that for sure, but for big clubs it not seem like there will be too big changes because top clubs are always coached by experienced coaches like Xavi.