Do antipsychotics increase the negative symptoms of schizophrenia (like apathy and social withdrawal)?

No. They don't increase negative symptoms. Unfortunately, they often don't do enough to decrease them either. The negative symptoms are part of the illness itself, not a medication side effect. After the antipsychotics control the positive symptoms, which they do a better job of treating, the negative symptoms are more easily noticed, but they are an inherent and impairing part of the illness.
Antipsychotics. Not increase symptoms, but high dose sedating agents can decrease energy and increase drowsiness, which could be concurs with negative symptoms or mood disorders.

Related Questions

If somebody has social withdrawal and apathy, does he have enough symptoms to have schizophrenia?

Social withdrawal. Not at all. You need to have disorganized thoughts & other psychotic symptoms to say maybe it is schizophrenia or bipolar do.
No. The schizophrenia diagnosis requires much more than apathy and social withdrawal. Usually, people diagnosed with schizophrenia suffer from reality-impairing symptoms such as hallucinations or delusions. In some cases, cognition is severely impaired resulting in very disorganized and illogical thoughts and behaviors.