For my situation, as part of the initial request to be seen by Mayo Doctors they collected my medical records. After a review they placed me with a team that met my specific health care needs. The team consisted of Oncologist, Thoracic Surgeon, and Radiation Oncology. While at Mayo I also found a pulmonologist that I wanted to be part of my care, since my other pulmonologist was at the previous medical office. I made a request to his unit to be his patient and was accepted by him.

@dongshiming, you ask "Can I request a particular provider?" I can answer how it works at Mayo Clinic.
Appointment specialists are specially trained to match you with the provider or group that's the best fit for your diagnosis and medical history. But you may wonder if you can request a specialist that you've read about or who's been recommended by a friend or colleague. Mayo Clinic can't honor all requests, but we try to when possible.

You can read more on this page of Frequently Asked Questions https://www.mayoclinic.org/appointments/faq