You probably could but it’s not the recommended way of preparing for the course. The classroom sessions are 3 days, and also the online path for rapid is 24h. The crash course (based on the materials is set on 12hours).
Although you might be able to pass the certification you will gain a lot more by understanding the materials, and this is done mostly through practice, do the exercises, read the docs and learning materials, and play around with it.
I think that depends on you, your background, … It might be possible. The question is: Is it beneficial? You should not learn Mendix to get a certification. You should learn it to be able to develop applications with it.
Getting used to the modeler and practice on some small demo applications is always beneficial. Many learning paths have a follow-along demo application that you can download and use.