it is very likely that PSG will play without Neymar because he was injured against Lille and it was his ankle, unfortunately he fell badly and I think that is where it is a reason for not being able to be there, however the combination of Mbappé + Messi is quite good, but Lille of France is one thing and Bayern another, Bayern will come out with everything, in fact it is the only thing they have left, fight for that I went in search of the UCL, and if they have to leave PSG on the road they will, Muller and his combo are clear about it.
I agree that when Mbappe plays well, he is unstoppable, and the fact that Bayern had to tackle very hard, proven by the red card as well, and basically had a very rough defense to make the players not only stop, but also cause fear in them with the idea "if you come in here, I will tackle you hard and you may get injured" mindset, that caused PSG to have a little bit of trouble.
In the second game they won't have the same defenders, and missing both one defender and their goalkeeper, so I am guessing they will be calmer. In that case, Mbappe who has been healed, could play and play for 90 minutes and you can stop him a few times, but he will get his chance to score.