I struggle to understand why United would want to buy a player like Osimhen: they just spent a ton of money less than 2 years ago to buy Højlund from Atalanta, for sure he is underperforming but he is still very young. If they buy Osimhen clearly he is going to be the main striker and Højlund would be benched. Oh, and let's not forger about Rashford. I don't know, I keep seeing a lot of confusion about United's strategy and management...
Manchester United's manager has no choice, he will need to sell many current players to sign new players and create a team that reflects his wishes. Keeping Højlund in the team would be a big mistake, just look at his performance;
Højlund = 24 games, 3 goals, 0 assists
With this excellent performance, it is better to sell him for a price that is at least 50% higher than what Manchester United spent on him, and then buy Osimhen or Viktor Gyökeres who is at Sporting and it was Ruben Amorin who brought him, so it would be easier to bring him to Manchester United. Regarding Rashford, they will probably sell him to Aston Villa, that would be a better option