Health insurance is mandatory for everyone visiting or living in Germany.
The following links is about medical cover for people on a long stay visa or permit.

Health Insurance Options in Germany – 2020

An article from “How to Germany” about the different health insurance options

How to cover your medical expenses in Germany

“Just Landed” wrote an article about health insurance in Germany

Tourist Health Cover

Tourist needs travel and medical insurance before they can apply for their Visa’s. Some of the options are your medical aid or a company like TIC. Please be aware of the requirements from the Embassy, not all credit card cover is accepted. When you need cover for 6 to 12 months, you can look at Klemmer.