@shreddies I would agree with everyone that it's a good idea to take subjects you enjoy and thus will most likely do well at.
And universities are not going to mind what GCSEs you have beyond maths and English.
That said, I am slightly surprised that the school will accept these choices; most schools IME want you to take at least one of the Ebacc subjects so it counts towards P8 – history, geography, MFL, CS.
I would also suggest that three subjects like that is going to be quite a bit of project work. It’s not common tbh to take more than one or two tech or creative subjects – but then that is often bc of the school’s P8 concerns (see above) so there are no slots.
Wrt his choices – does he love art? Is he really good at it and does it all the time for fun? Does he want to keep up art later in life? If no I suggest a rethink on that. Art is known as a massive thief of time so unless a student loves it and loves doing it then it’s tricky. I know a number of YP who loved art, took it for GCSE and ended up hating it bc it was all they did.
Look carefully at the DT spec – and bear in mind that it changed for 2019 GCSEs so only YP aged 21 or younger will have sat the current spec. A lot of DS2's mates took it (GCSE 2019 cohort) and were disappointed that the practical element, the thing they made, was less important than endless analysis of the design and why and how.
Music – does he play an instrument? If not I don’t think this is the best idea either. DD took music and was grade 5 in GCSE year; she found it not her easiest GCSE by a long way tho that was the old spec. Again, worth looking at the current spec. Drama which DD also took was quite a bit of external work with the group. DS2 did PE and that involved quite a bit of sport outside school – does he play sport – footy team, athletics, horse riding, swimming club? For DS this was not an issue as he did it anyway.
Would he be open to geography, history, business, CS instead of art/music/drama/PE?
Edited to add: @Cloouudnine no reason for an academic student not to take art btw – but note my points above.
Apologies for the essay!