People can get caught up in finding a better food for their dogs but certainly some kibbles are better quality than others. If your puppy is doing well on his current food, there's no need to switch him, but it's a matter of preference. Orijen is high protein, as you have pointed out, and some dogs do well, others don't seem to tolerate it as well. You won't know until you try. As for making your dog fat, that would be on you to provide the correct amount for your pup's frame. Most dogs can get fat on whatever food you're feeding if they get more than they need and the guidelines on the bags are just that, guidelines. If I fed my dogs what the bag suggests, they would be big old porch busters but it was a matter of watching their weight as they grew and adjusting the quantity based upon their body condition.
If the Orijen doesn't work for your puppy, you would just switch him over to something else. My pups switched from puppy to adult formula foods at about 5 months of age on the recommendation of their breeders but other breeders on here, or who people have gotten their pups from, suggest waiting until a year of age. If you got your puppy from a good breeder who is knowledgeable in such matters, you may want to check with the breeder as to when to switch from puppy to adult food. If you're switching to a food that is an All Life Stages food, that should have the correct mix of minerals for his still growing frame. There is a wide range of foods being fed to the dogs on here, from kibbles of many, many varieties, to homecooked to raw. You can only find the foods that work for your dog, there is no one best food. Speaking only for myself, my now adult dogs can eat a variety of different brands and I tend to switch things up with every bag so that should a recall occur with one brand, I have other brands I know I can switch to with no issues. There are a fair number on here who feed their dogs raw and would not dream of feeding kibble. It's all what works for you and your pup.
When you switch, you want to go pretty slow mixing his new food with the old food in gradually increasing ratios. Orijen has both more protein and more fat than your puppy is currently eating, so watch for loose stools or other GI symptoms as indicators that the switch is not going as hoped. Sometimes dogs get some loose stools because they've been given a little more food than they need, even 1/4 cup too much can be the difference between too much and just right.
Good luck, don't make yourself crazy with switching foods to find the "best" one- it can happen!