Restaurants and cafes: Restaurants are open on a Sunday and what could be better than having less crowd and no waiting. Yes, that’s right Sunday could be the best day to enjoy your meal or have a couple of drinks in a calm and silent restaurant. Or you can have a lovely afternoon reading a book and sipping coffee at some beautiful cafes in the downtown. Germans enjoy coffee with a piece of kuchen (cake). Most Sunday afternoons are reserved for this tradition of Kaffee-Kuchen.
Watch a movie: if you enjoy watching movies but not in deutsch/german, then Sundays can be your favourite day. Sundays are the best to watch a movie as there are quite a few English movie options. Its the day for English movies.
Fun activity: Germans have a huge fan-ship for the game of Football. With such crazy following, they too enjoy participating in some kind of indoor or outdoor activities, which is probably the reason :: they are part of some or the other Verein (association). If you are pro-active and enjoy playing games or into outdoor activities, then Sunday is a treat. There are many indoor and outdoor activities that you can consider doing on a Sunday, bowling, paint-ball, escape room, trekking, cycling, Nordic walking, spa and relaxation etc. There is a vast variety of options you can consider for a Sunday.