I have a now 1 year old labradoodle, got him at 8 weeks. Housebreaking basically comes down to making them want to pee outside. Treats and lots of praise every time they pee or poop outside, immediately when they're done (not when they run back to the house). Also right when they're finished use whatever your bathroom phrase is, and say it the same way every time, just say it once. "Potty" "Go pee" etc all work fine. Eventually you can use it if you're in a hurry or something to have them go.
The hard part is you have to set them up for success, and notice before hand if they need to go. Since your dog is older it shouldn't have to go as often as a puppy which is both easier and harder. Easier in that you don't have to take him out as much, harder as in you won't know when he needs to go as easily. Sniffing around is a common sign. My puppy often gets really hyper before he has to poop, not sure how common that is. Also get some enzymatic cleaner in case they have an accident, if they pee somewhere and it isn't perfectly cleaned, they'll smell it and decide that must be the bathroom.
We also put a bell by the door and rang it every time we went out. Eventually the puppy started ringing it when he had to go. He also rang it when he wanted to go out for a walk, so we ended up getting rid of it lol.
The other hard part is not punishing them if they do have an accident inside. Rubbing their nose in it may work sometimes, but I know at least one friend who did that strategy and his dog ended up just making sure he did it in another room or under a bed or something instead. He didn't understand "bathroom in house = bad" and thought it was "owner sees me bathroom = bad". Ended up making his problem WAY worse than it should have been. If you notice them about to pee you can say something to startle/interrupt them (not scare them) and quickly carry/lead them outside.
kikopup is a great youtube channel for all things dog training.
edit: Just realized you may be talking about calming the dog down inside rather than pee/poop. If that's what you're concerned with, exercise is your friend. A tired dog is a good dog. Long walks, lots of playing in the yard, etc. When he/she IS being calm and good in the house, a treat dropped by his nose is a good idea. No big show of it or praise, just a simple reward for being calm. We were also advised of a strategy when we got the puppy where you hold him in a sit posture in front of you, hand on his chest. If he struggles, hold a bit tighter, when he relaxes, loosen your grip. Pair it up with a command like "settle" said in a calm tone, and eventually when you get him in that position he'll calm right down. Not sure how well that will work on an adult dog that may not really trust you yet, so be cautious implementing it.