It was sourced as a potential place of study by those who were also considering Bocconi (a while ago, my DD her A levels in 2022 and is humanities so was not of interest to her as an option). Whilst Bocconi rated higher, the reputation of IE was considered good, though I myself am not a follower of world rankings.
But, most who applied did have a native home connection/relatives, the home living for those is real, some of her peers staying with GPs. That said, it is down to the personality of your DC as the PP has said, on how open they are to mixing from an independent living basis.
Even Y3 of being taught solely in Spanish in Spain is tough for non-natives, and different parts of Spain will through up regional dialect challenges, which mine is experiencing now, and her Spanish is very strong. Nothing insurmountable, but worth being conscious about as there are no concessions made for non-Spanish students when studying competitive course modules.
Good luck to your DC though for considering his options as the UK is not the be all it used to be, even with access to SF.
Re the point on world class universities @TizerorFizz , I don't know the answer. Anecdotally, I can say that those within my DD's peer group of study are not experiencing an issue in securing internships and other opportunities, These types of places tend to approach academic study with a more entrepreneurial business style, making students more marketable vs less (in my anecdotal opinion). World rankings are not the issue, if their conversion in the recruitment process is leading to results.