Nagyerdei Park
You will find detailed location and information here: https://surl.li/qrouq
The park belongs to a large area of forests that are already about 80 years old.
In the summer, around the lake, they host wine and jazz festivals, that are worth your attention.
A big advantage, is that there are many different food courts, a tram stop, a zoo, an aquapark, a stadion and a university nearby.
Also, in the park you can find a large playground, a small cafe and a place for sport)