I'm looking for recommendations where the story is primarily set in a single location.
For example, scenarios where the MC are stranded or isolated, like being on a deserted island, in a locked room, in a bunker post-apocalypse, or trapped in one place for some reason.
Bonus points for long stories with tons of drama, character growth etc.
Most short stories take place in a single location (actually, a single event). But that goes against your desire for long stories.
"New Society, New Rules" takes place in a single location — an uninhabited island. It's 47.5K words. https://storiesonline.net/s/12326/new-society-new-rules-erotica-sex-story
"Girl's Camp" takes place in a single location — a camp. It's not real long at 30k words. https://storiesonline.net/s/10581/girls-camp
Alan Joyal's two Ishtar stories from the Swarm Cycle universe may fit the bill.
The first (A Peril at Ishtar) is partially in pods on the way to Ishtar, but the second (A Crisis at Ishtar)is all in the one underground settlement on planet.