But let's step outside obvious physical limiations to look at a few examples where confinement is psychological. Emotional life and death stakes can be just as effective.
Sally can be confined by a family, a tribe, or a gang. The situation can be an abusive or an intolerable person she needs to flee from. She may simply need to escape to pursue the career she loves or marry the man of her dreams.
Dick can feel trapped in an airplane seat. Add an obnoxious rowmate and his discomfort increases. Replace the obnoxious stranger with an angry spouse and your characters are strapped in for a few hours of heated debate or icy silence.
Being confined in a car can have the same effect. Characters often have intense and important conversations while strapped inside. Being confined in a train, elevator, or waiting room can provide Dick with ample time to think something through as well.
Dick might want to break free of romantic relationship or marriage. Depending on his personality type and childhood wounds, he might find commitment suffocating. It can be as simple as Dick not liking that his romantic options have narrowed or been eliminated, so he refuses to propose to a girl he loves. He’ll live with her but he doesn’t like the prison bars that marriage suggests.
If Jane sees marriage as a desirable bond, a sign that Dick values their relationship and promises to always have her back, she won’t understand his reluctance. This provides terrific tension in a romance or romantic subplot. Dick and Jane, as well as the supporting cast, can argue whether marriage entraps or frees them. Dick can overcome his internal resistance and give in. Dick and Jane can agree that their commitment to each other is more important than the piece of paper. Or, their differing belief systems and needs are a deal breaker and they end the relationship.
Sally might want to break free of a confining friendship. If Sally is the type of easy-breezy personality that loves to be around lots of people and considers twenty people her best friend, she might befriend Jane who values one tight, soul-sister over lesser acquaintances. Confine these two in an apartment or a college dorm and the conflict increases. Whether physically confined or emotionally confined, their differing needs and definitions of loyalty and trust provide obstacles to continuing their friendship. It can be explored in a sweet literary story about why friendships fail. Jane could cause problems for Sally, the protagonist, in other genres as Sally negotiates her exacting friend’s emotional neediness while solving an unrelated story problem. This claustrophobic dynamic has been explored in horror films about scary roommates, but it can also factor in virtually any plot line. Pairing friends with differing connection needs creates believable conflict.
Jane might want to escape a confining job. She may be afraid to leave a lucrative career but imprisoned by the monotony or lack of challenge. She may love the job but hate her boss or coworkers. The entrapment will either force to her make a life changing career move or renegotiate her reality within the confines of her job.
If going home feels like entering a prison, Jane isn’t going to enjoy going there for a holiday meal, much less a week. She may be forced to return home to take care of an ailing parent. The situation makes her feel like she is being strangled, particularly if irritating siblings insist on visiting. Emotional bombs will burst.
Setting and situation choices can force your character to make decisions or take actions they otherwise would ignore. As the character's social, psychological, or physical noose tightens, the reader's tension grows along with it and they keep turning the page to relieve their own anxiety.