To pass an MCD - Integration and API Associate, MCD - API Design Associate or MCA - Solution Design Specialist level exam, we strongly recommend taking the corresponding course. In fact, the MCA - Solution Design Specialist certification INCLUDES the course with the exam: it is not possible to purchase the MCA - Solution Design Specialist as a standalone exam. See the main certification page for further details. Taking the training is no guarantee to pass, but few people pass without taking the training.
To pass a Professional level exam, it takes much more than training. The individual will need not only MuleSoft training but also significant hands-on project experience with MuleSoft products after the training. There are classes such as Anypoint Platform Development: Advanced to help increase knowledge, but again, the exam is meant to test real expertise, not just classroom knowledge. Typically, a successful candidate for the MCD - Integration Professional certification has at least 1-2 years of consistent development work and experience.