Hello, Kyle!
Welcome to Microsoft’s Community. We are more than happy to help you.
As we understand, you want to receive information about MOS.
If you want to achieve the Certification as Microsoft Office Specialist, MOS Expert and MOS Master, you can check the following link:
Earn a Microsoft Office Specialist (MOS) certification
About how common the Microsoft Office Specialist Master Certification is, we suggest you contact the Certiport Support as they are the team in charge of MOS Exams and Certifications.
Here you can find additional details: Microsoft Office Specialist :: Certiport (pearsonvue.com)
You can visualize each one of the links and check the best option for you. Also, in each link mention the plan with the required Exams in "certification details" and the title you will achieve.
In case we do not receive a response, the thread will be closed and locked after one business day.
Kind regards,