I don't know how you come up with that idea that PSG can't win in overtime. It is an opinion you say, wondering what that opinion is based on. A small disadvantage I see for PSG is that they lost two players which otherwise would play. Pacho played most games and Hernandez was an important option for Enrique, now they have to get along without them but when you see their player names, this shouldn't be a big problem for them.
Real Madrid was almost forced into overtime against Dortmund. Anyone who saw the chance that Sabitzer had and how centimetres decided that the ball did not go into the back of the net, my opinion is that Real Madrid first has to try to get into overtime and not the other way around.
what i mean is that real madrid almost always win in these kinds of tournaments in matches that go to extra time or penalty shootouts after a draw. if you look at the stats you will understand what i mean. real madrid is very good at this. let's say in their match against psg the 90 minutes ended in a draw with a score like 2-2 or 3-3. then they will probably manage to be the team that goes to the final either in extra time or in penalty shootouts.