If users are to find your business on Google, it makes sense to create a Google My Business listing. This way, customers can get more information directly on the search results page and also book an appointment with you immediately.
Requirements
You must have a Google account to create a My Business listing. Then you can create a free listing for your business at https://www.google.com/intl/de_de/business/. To ensure it is a real location, Google will send you a postcard with a code. Once you have added this code to your My Business listing, the listing will be published.
Google search results page with Google My Business listing on the right side:

Setting up the booking link
To enter the link to your online booking page, you can log in at the address mentioned above and add your online booking page URL under "Info".

After that, customers who find your business during a Google search can immediately book appointments.