yep, that's right. everything you say is true that Real Madrid is currently a little comfortable even though they only have an 8 point difference with Barcelona, but even though they will lose it still won't change the position of these two teams and I think Ancelotti as Madrid coach prefers to keep physical players who can be relied on at the UCL.
In the El Clasico match, I am sure that Real Madrid will get a winning result even though they only use second tier players, because in the previous several meetings, Madrid was still able to beat Barcelona and the worst result in the El Clasico match will be a draw and I want to guess that Vinic will only will sit on the bench.
8 points is too much for Real Madrid, they will not allow anyone to get close enough to question their championship. There are still a few days before the match, this will be enough for Real to recover after the match with City, and Barcelona will also not be in the best condition after the defeat to PSG. And besides, the match will take place in Madrid, so I don’t think that Barcelona has a chance to win this match.