You are right that experience matters in this match but don’t you think that even Bayern Munich players also have experience for their long time in the competition also, they do qualify every year and they get to have that experience no matter how little. Even if their coach Vincent Kompany is not that experienced to put them through, they can at least be able to show some better quality in the match because of their vast experience. Hanso Flick may be experienced but playing against a team like Bayern Munich does not give him guarantee that he can win easily. I think the match is going to be a very tough and even one and we can’t really tell which team can prevail at at this point.
No one is saying an experience can make a team win easily but experience will surely put them ahead even before the game, they might not have it easy but there's always a hope of winning . Let's take Mancity for example, what did you notice after Pep Guardiola joined the club?? they won their first UCL doesn't that ring a bell about experience.
I'm not actually saying they will win their upcoming game easily (Barca) but I think they would and at the same time Flick is going to be facing his Former club(he should definitely know the playing pattern), that's actually my thought towards this game.