I don't think Bayern Munich can get an easy win against Barcelona, and it could even be that Barcelona will get the match because even though they had to lose Ter Stegen who had a long injury but, Barcelona is still the best in La Liga so far, and they have a very productive front line. I don't know who will be the starter between Inaki Pena and Wojciech Szczesny but I'm pretty hopeful that Szczesny will be the one chosen because he has experience and maybe that will be very useful when playing against Munich (and other matches).
In the context of one match, anything can happen, we saw that Bayern, Real can lose to seemingly weaker opponents, one mistake is enough to concede and play well in defense. And there is no point in predicting the results between such opponents as Barcelona and Bayern, these are equal teams, I think that their confrontation will take place without a clear advantage of one of the teams, the absence of Ter Stegen can be a big problem, but despite the fact that the match will be held in Spain, I cannot give an advantage to either team.