Can you get a Masters degree or Ph.D using mostly CLEP?

No, you cannot get a Master's degree or Ph.D. using mostly CLEP exams. While CLEP exams can grant college credit for undergraduate coursework, they are generally not accepted in lieu of the significant research, coursework, and thesis/dissertation requirements of graduate-level programs.

Graduate schools focus on advanced study and original contributions to a field, which CLEP exams cannot demonstrate. They might accept a few CLEP credits to fulfill general education requirements at the Master's level, but this would be a very small portion of the overall degree requirements. A Ph.D. program would almost certainly not accept any CLEP credit.