The iPhone 7 Plus ( like the iPhone 7) hasn’t got a 3.5mm headphone jack. You’ll need to use Lightning headphones ( a pair of Lightning-based EarPods are included with the phone) , or go wireless, or use an adaptor.
The iPhone 7 Plus is an overweight brick at 188 grams. Compare that to the OnePlus 3T at only 158 grams, 30 grams less with the same display size. I wouldn’t want to spend an hour reading a book on this iPhone. The Huawei Mate 8, a 6 inch phone is only 185 grams, bigger but lighter