Some MBA programs require students to have work experience, some for one year, some for three years or more. MBA programs usually have relatively low requirements for GPA. As a result, students with low GPA can apply for an MBA degree from a better school through a gap year.
I think it is very difficult to go to graduate school after working for a year or a few years, because the work comes with setting up a family, supporting parents, and raising children. All these make it impossible to concentrate on studying, so I think it is unrealistic to work first and then go to graduate school. Of course, some projects require several years of work experience. These projects require special planning.