In principle, this is quite possible, have you ever heard of a tulpa? If you start every day to imagine a person and talk to him, then this is quite real.
Schizophrenia is a very serious disease caused by many factors, of which the genetic one is perhaps the most important. This means that it is simply impossible to imitate or call it yourself. I cannot even theoretically imagine this. Hallucinations can be induced artificially only with the help of psychotropic drugs. Delirium also does not happen at will. In other words, extraneous voices will not visit you if you are really healthy. Of course, forced long-term loneliness can shake even the strongest psyche, but it will not lead to schizophrenia in a person who is not prone to this disease, corresponding without heredity and genetic predisposition. However, if one of your relatives (even distant ones) had schizophrenia, or if you already have mental problems, then such an experiment on yourself may well become a trigger for the disease.
No. You can become a strange person and develop the habit of talking to yourself, but this will not mean the appearance of schizophrenia. It just means that you have strange habits.
Schizophrenia is a very definite ailment, with very characteristic symptoms. They can be "provoked" (if there is a predisposition to this disorder); they can be mimicked pharmacologically, but they cannot be "evolved at will".