This visa type is intended to provide graduates (of a relevant course) the opportunity to find work opportunities in the UK. The study condition of the Graduate Route visa explains you cannot study any course which could be sponsored by a study provider under the Student Route visa category.
Study is restricted under the terms and conditions of the Graduate Route visa.
Examples of permitted study are:
You will need to contact the course provider to clarify whether you can or cannot study your desired course as a Graduate Route visa holder.