Overall, Souma didn't change while in Holly Heights. Were he there for a little longer, he might have, but he took things in stride as he always does rather than letting anything bother him.
When he first arrived, he discovered that he was no longer an only child and suddenly had two dads. His family - Shouyou Hinata, Kazuki Mikabe, and Natsuki Shinomiya - were people he grew close to over his brief period there, and were... interesting. Both Shouyou and Natsuki were largely banned from cooking, for everyone's own good, but especially Natsuki.
During his stay, brief as it was, Souma largely worked on keeping his knife skills sharp, and learning more about different cuisines for when he was able to go home eventually. A lot of time was also spent with Shouyou learning about volleyball, and hanging out with his dads, but he did make a decent amount of friends and acquaintances. Easy enough, when you're
pretty friendly and don't let the aloof or prickly types of people be offputting.
This was made much easier when he opted to
offer cooking lessons to the community, come Thanksgiving. And, as Souma is wont to do, he also asked for challenges for things to make. Cooking Yukihira was a large success, with multiple people responding and seeking out free food and free cooking lessons. There were some... interesting folks, really, where Souma wound up accidentally adopting a stray cat (Rin Hoshizora), and gave a promise to finally get Rin Kobayashi his udon after offering to make it for him previously.
The last thing of real note, besides his cooking lessons and free food (done with a great deal of people who replied to his offer, as well as a few stragglers like Tooru Oikawa), was a series of... unfortunate events.
The Kominato-Sugane household
had a cooking disaster, which Souma saw after the fact. Rather than leave his household helpless,
Haruichi came to Souma for expedited lessons.
And then Souma
betrayed Haruichi, though his brother is right - scientifically, tomatoes are a fruit.
Shortly thereafter, however, Souma was sent back home. (And then the game closed with no resolution and here we are now, bitter and taking our CRAU elsewhere since I couldn't app him back.)