Of course, because in football there is no team that cannot be beaten even though they have a very perfect squad, Madrid so far has efficiency in recruiting the players they want to buy and most of the players recruited are the needs of the team so that it will make their team stronger every season so far.
It is true. No team that is impossible to be defeated. Although Real Madrid has a stronger squad, it doesn't mean they will win the UCL trophy automatically. There should be a chance that they will be eliminated by other teams. Man City, Bayern Munich, and Inter Milan are the examples of few teams that look like very possible to beat Real Madrid.
Regarding that we will talk about the percentage of who has a higher chance of becoming champion in the Champions League. However, it is not automatically the case that the team that has a high percentage of chances will become champions, they need to prove themselves by playing well too. There are several teams that have a high percentage of opportunities but they ultimately fail too, let's say Leverkusen last season in the Europa League, they lost in the final round.
These are examples of different competitions, and let's take the example of the Champions League itself. Last season, Manchester City was the team with the highest percentage to become champions, but they also failed because they lost to the team with the percentage below them, Real Madrid. It only opens up opportunities, what determines is the game on the field. Whoever is better will win, don't forget other things such as mentality and luck which are sometimes determining factors.