I think you have a point, especially since Xavi manages Barcelona. Xavi understands what his team needs to win El Clasico and that has inspired the team to win it more often. The first El Clasico match was played at Barcelona's home ground, that's something that might give them the lead even though it's still possible that Barcelona won't be able to play all their best players.
Xavi knows the gravity of the match, which is why he prepares very well for the El Clasico match, because irrespective of Barcelona's form, they are always given Real Madrid a tough time because Barcelona won four out of their last five El Clasico matches.
Real Madrid is dangerous not because of Bellingham and Vinicius, but players like Valverde and Kross can also have a positive impact on the game. But before the El Clasico match, Real Madrid and Barcelona will play two other matches in two different competitions. Player rotation is expected and may be considered, which is a good thing ahead of El Clasico.
Real Madrid is on form this season, and since most of their injured players are back and with experienced players like Toni Kroos and Modric in Real Madrid's midfield, I think they will take some revenge after the last 3-0 victory Barcelona had in the club friendlies.