Moving from one club to another is a huge change in a player's career. A player performing well at one club won't necessarily find that their strong performances carry over to their new club, as they may not fit in as well, tactically, as well as socially.
In the case of Leeds United 's new signing Rasmus Kristensen, he has an advantage over many new signings in this regard. That's due to the fact that he is coming to play under a manager he has already worked with and to join a team where he will have a friend already, since another of Leeds' new signings, Brenden Aaronson was a friend and teammate at RB Salzburg.
In fact, Kristensen revealed that the two players lived 'in the same building' in Austria as he spoke to Sky Sports: