He needs no introduction is what Liverpool hopes for, but I think players like Isak and Wirtz still can be risky, they are not Messi or Haaland or Ronaldo. You could see that Mbappe had some problems when he arrived in Madrid. It was not like he immediately played his best game. I think Wirtz will need some time because he was perfectly put to use in Leverkusen's game and the game was made for him while the competition on his position was limited there. In Liverpool he will be a beginner like everyone else and he has to prove himself. The same is probably true for Isak.
If Wiltz did not make an instant impact, I would understand because it takes some players time to adapt after moving to a different league and team. However, I don't think it will be the case with Isak. He knows the league like the back of his palm, and the way Liverpool plays, I think it will perfectly suit him. I'm beginning to picture him in Liverpool's jersey already.
Some players don't need much time to adapt to a new environment in sports. It's true that for some players it is difficult to play their best when new players are around them, but I believe that the best of the best players don't need a few games. They can use their skill from the very first game they are playing for a new team and immediately have a positive impact on the game. All this patience is needed when players are highly sensitive to what happens around them. Those with incredible mental strength are instantly focused on their new task and will deliver.