Should everyone get a second opinion for a cervical cancer diagnosis?

No. The diagnosis of cervical cancer is made by pathological examination of a biopsy. Ask to see this report. If it says cancer, a second opinion will not change that. You may, however, wish to get a second opinion about proposed treatment for precancerous cells, which should not be confused with or called cancer. You may also wish to get a second opinion about a proposed treatment of true cancer.
Second opinions. Are never a bad idea, but not required or even necessary if you have confidence, trust, and belief in the provider you have. If you have questions, do not feel comfortable asking, or you lack that confidence, get another opinion.