If, hypothetically, that was the case - then why would a club spend an enormous fee on signing a player only to loan them to a rival? If a club did indeed make an offer the club felt bound to accept, then the player would unquestionably involved in the buying club’s first team squad.
If Manchester United spent, let’s say, £70m of their limited funds on a striker, you can be sure he will be at least on the bench come the first game of the season. Not even the richest clubs like Real Madrid, Manchester City or PSG would spend such an astronomical sum and then let a rival club use their expensive new asset free of charge.
It makes absolutely zero sense.