Help me choose semi-formals for my younger brother on his 1st job

My younger brother (early 20's) is starting his internship at a very well known company soon, and as a birthday gift, he asked me for some semi-formal trousers. I suggested chinos and he said thats whats he looking for. I am thinking of gifting him an entire set, shirts (or whatever fits the definition of semi formal), trousers and a new pair of shows that comforting and formal enough to be wore at work. His work is in San Francisco Bay Area where the culture is pretty laid back, AFAIK.

He's almost 5"5', south Asian and lean (thin) but slightly muscular. Has done a lot of things to his hairdo to make it curly. He's in Pennsylvania currently.

Would someone please advise what can I get him?