It can make a big difference. It'll give you something to love, that loves you back. Provide entertainment. Give you structure, a routine, responsibility.
But make sure you're up to it. Pets aren't easy. Baby animals especially are not easy. Puppies require a ton of work and energy. You have to be patient. You have to be prepared to walk them a lot and clean up accidents, because even the best puppies will have them. It's especially difficult this time of year, with weather turning bad.
If you have energy issues or patience issues, maybe it'll overwhelm you. But there are other pets that need less attention but are just as rewarding. Guinea pigs can be great.
I'm speaking from experience. I'm not a dog person, but I got talked into a puppy a couple of years ago. Everyone said it was just what I needed. It was a fucking nightmare for me. I knew I didn't have the energy for it, but I did it anyway. I had to give it up, but it has a very good home now.
I'm currently going through kitten hell. And I love cats. I've had them my whole life. I love this kitten. But my depression is not compatible with caring for other living things. I'm so sad I got talked into this. My 15 year old cat died last Christmas, and I knew I wasn't ready. I didn't want to get another pet at all. I figured it would make it easier to end it when I was ready if I didn't have that to worry about. Now I'm in this mess again.
Then again, the kitten is effectively keeping me alive right now because I don't know what else to do, so...