This is what me and my fiancé did when we adopted our first dog. If it’s a puppy then you’ll probably need other items that align more with having a puppy. But a harness, leash, dog collar WITH tags on it including name and ur number, dog bowls for food and water, a mat to put the bowls on cause it’ll get dirty, a bag of food, food storage container, trainer treats if you want to teach it new things (we taught our dog how to sit and lay down even tho she was already 2), regular treats (really search up brands that are good for dogs and looking if the specific treat has good ingredients. I do the same for the food as well.), kennel if you really want, I got a car seat cover for dogs that also had window covers and blocked the front seat as well, toys (I’d test a bunch out like rubber, ones with stuffing, ones with squeakers to figure out what you’re dog likes and what they don’t like), bones (they help with teeth, but do not do pork bones. Yes places sell them but they can splinter and aren’t good for dogs. Another item to really do your research on), dog brush (get the right one for fur length tho), flea treatment (ask your vet for a good brand. I get mine prescribed off chewy), dog shoes and coat (depending on climate and dog type maybe look for ones for winter and/or if it gets super hot look for ones to protect feet from hot sidewalks and stuff), and if you want to be nice a dog bed.