If you are not enrolled in a graduate training program accredited by California's ACGME, you will not be able to pursue clinical practice in the state until you obtain a doctor and surgeon's license. All allopathic doctors must receive a license from the Board before they can legally practice medicine and examine patients without supervision. Unfortunately, a medical license is not something that is automatically granted upon receiving a medical degree. Each country has different requirements and regulations, but obtaining a license will normally require you to complete at least one year of residency.
If you want to obtain your medical license in the United States, you must pass Step 1 of the USMLE, Step 2 CK of the USMLE, and Step 3 of the USMLE, as well as at least one year of a medical residency program. The requirements vary slightly from state to state, and are also different for international medical graduates. This means that if you want to obtain a medical license and become a practicing doctor, you cannot avoid the residency application and interview processes, as well as at least minimal residency training. A state medical license is an incredibly valuable credential and it cannot be obtained without at least one year of residency.
As Academic Medicine points out, a doctor without a medical license cannot even examine a patient with supervision - something they could do when they were still a medical student. The Board can issue you a special permit if you are an international doctor who does not currently qualify for a physician and surgeon license in California. Alternatively, if you graduated from a Canadian medical school or have completed 24 credit months (international medical school graduates) of Board-approved graduate training, and are enrolled in a California graduate training program accredited by the Accreditation Council for Graduate Medical Education (ACGME), you are eligible to obtain a graduate training license. Graduates of Canadian medical schools or those who have completed 24 credit months (international medical school graduates) of graduate training approved by the Board who do not have a doctor and surgeon license, have passed all the required exams, and are accepted into a graduate training program accredited by the Accreditation Council for Graduate Medical Education (ACGME) in California must obtain a graduate training license (PTL) within 180 days of enrollment.
For most high-paying jobs that involve leadership or responsibility, you'll have to complete a residency and even practice medicine in your specialty to add value as a non-clinical doctor. A medical school, hospital, academic medical center, or approved scholarship training program in California must sponsor your special permit application. In general, doctors who leave medicine tend to take risks and feel comfortable reinventing themselves professionally. Doctors learn all their lives and there will always be something new to discover or learn in the field of medicine.
In most cases, you will have to do additional training, although as a doctor you will have an advantage over people who are just starting out in medicine.