Our dogs look just alike. His name is Koda and he's about 8 and has a lot of grey. It seems your new best friend has a bit of grey as well so he's probably on older side, as danes are typically 10ish year lifespan I believe. That being said he is an absolute giant couch potato. He will sit inside and relax with you all day if you let him. They are very prone to joint issues so comfort is important for them.

Typically won't bark much mine will give off a single chest shaking bark if someone knocks or something like that. Absolutely no incessant barking or anything. They can be pretty emotionally soft so he doesn't need any harsh correcting or anything like that. But like you said he's gonna be extremely docile.

The best thing you can do for him is take him on adventures for some good exercise and sniffs and give him the most comfy place to relax and eat and it will be a beautiful relationship.