We do not know how rashford will play in barcelona. But we have seen that Rashford has been trying to come to Barcelona for a long time. And he is very interested in playing for this club. So I believe that Rashford will do his best to perform well in Barcelona. He will become more diligent.
I am waiting to see how Hansi flick uses rashford. If he changes the Lewandowski-Yamal-Raphinha trio in attack, he will make a big mistake. All three of these played excellently in the barcelona jersey last season. Perhaps Rashford will get a place in the squad if any player gets injured. Or he will come on the field in the second half.
Marcus Rashford seems unlikely to have much difficulty adapting if he joins Barcelona, he possesses quality above that of most other players. Hansi Flick might still rely on Raphinha, Lewandowski, and Yamal, with Rashford as an alternative option. However, given Lewandowski advanced age, there might be hope for Rashford to become a starter more often.
Regardless, Rashford recruitment would be a very beneficial deal for Barcelona. They'd be getting an experienced player at the peak of his career, and his transfer value isn't too expensive. Hansi Flick could potentially push Rashford to rediscover his best form, so after his loan spell ends, Barcelona would genuinely deserve to make his move permanent.