Imagine that a character is trapped somewhere. It could be a small room, a well, a crashed car, a stuck elevator, or any number of small claustrophobic spaces.
They have been stuck there for at least thirty minutes when you start writing your story. This is important because they already have to be nervous at this point.
All the other details are up to you, but there are many important factors to consider. Can they communicate with anyone on the outside? Do they need to be somewhere else urgently? Are they alone in that space? How did they get there? Is this a matter of life and death or just an inconvenience? Are they naturally a little claustrophobic?
Set a timer for 15 minutes while writing this and find out where the prompt takes you. When the time is up the character might still be stuck in the space or they could be free. That is up to you.
Have fun!