Learning German language to kids

Hello,
I have 2 kids aged 6 and 7.
We are moving to Berlin in 2 months and planning to stay there. Kids will get enrolled in a school of course.
I wanted to kindly ask if there is something that I can do in these 2 months to facilitate the German learning language process for my kids, like some online materials or any other idea that would help them getting acquainted with the German language.
P.s they know now only french.
Thank you so much
George

Just two months before the move is pretty short to start with the language preparation. But you should get them as much exposure as possible. Your profile says you are currently in Beirut, Lebanon: The Goethe Institute there can certainly help you find suitable classes, resources and/or teachers.
Since it is obviously impossible to learn a language well enough in just two months, you should after moving enroll them in preparatory classes for foreign kids, which some public schools offer (free of charge). Depending on their abilities, they will then change to regular classes after a few months to a year.

Thank you very much