The reason why Real Madrid lose against Juventus is Real Madrid use a strategy where it depend on Bellingham as an attacking midfielder. They're more comfortable when the midfielder backing up other midfielder and working together.
But it's clear there are so many chances in Real Madrid, but their strikers weren't able to maximize it.
This is a new debut for Jude Bellingham in Madrid, because it is still in a friendly match coach Carlo Ancelotti trying to find the right position for him, Ancelotti has made several game options throughout pre-season to find the maximum performance from all players. However, this defeat will see Ancelotti return to make more correcting in his first team before LaLiga starts
By looking at the quality and performance of new players in friendly matches like this, of course Ancelotti will be able to know the players readiness to play in real matches when the league starts later. So yes, even though the results may still not be optimal but still, it looks like Bellingham will also get his place in the Real Madrid main squad later. Unless Bellingham suffers an injury like Guler, then surely it will be a very unfortunate incident and will probably be regretted too.