For Arsenal it's a good choice because they lack such quality and Rodrygo would upgrade their team and probably aid them to win the EPL title but it's a big lose for Real Madrid. We'll from what I've observed in the FIFA Club World Cup, Xabi Alonso haven't given Rodrygo more playing time so it could mean that Rodrygo is not welcomed in his squad and needs to leave. I might not be right but the rumours of Rodrygo leaving is getting intense so there's this slight believe I've got that he'll leave
There have been speculation about winning the premier league next season by Arsenal seeing that they are making some very fantastic signings and I agree that it is a good reason to think that they have a chance to win but for me I will rather slow down because last season we saw something similar with Madrid and so I would not want to rush into the conclusion that Arsenal will win the Premier League, Real Madrid had very smart signing last season and yet did not win the champions league so it is possible Arsenal may only fo better than they did last season, because even last season they had very good players and yet did not win the Premier league neither any other trophy.