Yeah as we know against PSG Real Madrid's defense made a lot of mistakes that led to goals and this was done several times --- with a great performance from PSG to bulldoze Real Madrid mercilessly.
I'm not sure how Chelsea will do against PSG in the final, but it's likely that Chelsea will have a better match than Real Madrid, it's just that in the final many are favoring PSG as the winner.
It's understandable that many would favor PSG in the final after what we saw from them against Real Madrid. But Chelsea shouldn't be underestimated either. Their progress isn't due to mere coincidence, but rather to the hard work they've put in to get here. Honestly, I personally predict PSG will win the final and lift the Club World Cup trophy. But I'm pretty sure PSG won't be able to score many goals against Chelsea. Because I believe Chelsea's squad depth, which is quite flexible and has many options to adjust their strategy, Chelsea will at least be able to defend better. But I'm not sure whether Chelsea will be able to penetrate PSG's defense.