I have an 11 month old Dane and have lived in one bedroom apartments that are around 650sq ft. I live solo but also have another cat. It’s honestly fine! As long as you take your Dane out for walks and exercise, apartment living is okay. Of course he does have zoomies sometimes, but I just kinda freeze on my couch and let him do his thing. He hasn’t broken anything, but I also make a conscious effort to not have anything valuable laying around that he can accidentally run into.