There is no general rule on how therapy works or is supposed to work and there is also no general rule on whether one needs therapy when they are experiencing emotional issues. Some people get better without therapy, others need therapy to get better.

One's individual therapy experience depends on various factors. It certainly depends on whether the therapist and the client are a good match, on whether the client is ready to do the healing work, on the severity of the clients problems, on therapy settings etc.

Sometimes people do feel worse before they get better and sometimes it doesn't happen. I'd say from my own experience that "getting worse" shouldn't push you in the place that is too dark and depressing. What is usually meant by "getting worse" is that a certain amount of pain that has been repressed before often starts surfacing, but pain itself is not necessarily the same as "getting worse". When it gets released it may hurt, but it also feels somewhat liberating. If there is no sense of release and clarity then pain turns into a meaningless suffering, which is an indication that therapy took the wrong turn.

If you just feel more depressed with no clarity, no new insight into your state of mind or your life situation, it might be best to seek help from another professional or outside of psychotherapy field altogether.