After graduating in Germany, do I need to find a company willing to sponsor my visa, and is there a particular time frame to get a job?

Yes, after graduating in Germany, you must find a job related to your degree with an employer willing to support your work visa or EU Blue Card application.

You have an 18-month Job Seeker Residence Permit after graduation to stay in Germany and search for a suitable job. During this period, you can work in any job to support yourself, but you need to secure a relevant position within these 18 months to transition to a work visa.