Sure. You can try searching on various platforms dedicated to fanfiction. However, the quality can vary a great deal. Some might be written by novice writers who are just starting to explore the concept of combining these two very different universes, while others could be really well - crafted with great character development and engaging storylines. It's all about finding the ones that suit your taste.
There are probably some. I've seen a lot of crossover fanfics in general. For the 'naruto x dark magician girl' ones, they might not be as common as some other crossovers, but if you dig deep enough in the fanfic communities, you'll find them. They could have interesting scenarios, like the Dark Magician Girl getting transported to the Naruto world and having to adapt, or Naruto somehow ending up in a world full of magic like hers.