Lets start with the Rapid developer course: https://academy.mendix.com/link/paths/31/Become-a-Rapid-Developer
Where after you can take the rapid developer exam https://academy.mendix.com/link/certifications/23/rapid
After this start practicing Mendix, best done by joining a project for a few (2-3) months
In mean while; take the intermediate paths https://academy.mendix.com/link/paths
The knowledge checks of these learning paths give a decent overview of the level of questions
Ensure you have ~4 months of practice
Enroll exam here https://academy.mendix.com/link/certifications/22/intermediate