I agree with your last paragraph. PSG team will have to play very carefully even though they will play as favourites in the final and Chelsea has made it to the final so it is possible for them to make any accident. If Chelsea wins then you cannot call it a complete accident because they have played against strong teams in the past matches and have made it to the final by defeating them. If you see the great moments of Chelsea young players you can easily guess about their future and how aggressive they can be to win the match. In the semi-final surrounded by a very strong wall of PSG defense a great team like Real Madrid could not break that wall even though they have world-famous and expensive players. Chelsea is lucky we must admit this but if luck goes in their favor in the final then it will not be surprising.
The media would be in a frenzy if Chelsea surprised everyone by winning the final against PSG. Everyone seems pretty confident that PSG will win the Club World Cup. So, most of us would be surprised if Chelsea managed to break through PSG's defense. Even if Chelsea loses but manages to score against PSG, they will still be considered a team that has improved significantly. Bayern and Real Madrid couldn't even break through PSG's defense. So, if Chelsea manages to do so, it would be a slight advantage over both of them. I can't wait for tomorrow. And I'm sure you all do too.
And another thing about Chelsea's players is their youthful spirit, which could have motivated them even more if they had reached the final. And now they're in the final, and I'm pretty sure Chelsea's young players will be truly ambitious to win. They won't be afraid of PSG's strength, which they already know. That's just how young players are. It's just that young players are prone to giving up when they concede too early.