Children under 10 do not need a test for entry.
Paraguay is also allowing those who've had a positive (and fully recovered) diagnosis of the disease to enter with a medical certificate showing the positive result within 14-90 days of arrival.
All passengers, both foreigners and citizens, will need to complete the online Health Declaration Form between at most 24 hours and at least 30 minutes before the flight.
Paraguay Tourist visa is not required for citizens of Germany for a stay up to 90 days
Check with your airline in case you have connecting flights overseas as part of your journey to Paraguay. It may be the case that countries you pass through en route to your destination may require a separate transit visa. Please refer to visa requirements of the specific country.