As the other guy said, they would improve your reception, but they can also improve your broadcasting. This one mounts right onto the radio and is pretty good. This one is something that you can mount up high, outside your vehicle, or strapped to a pole on your house. It requires an adapter but significantly improves reception. You can get generic ones for less. Sometimes they work, sometimes they fry your radio when you try to broadcast. I’d stick with name brand.

PS, you can’t broadcast without a license, so don’t try. You can get a GMRS license for like $60 and it’s good for ten years. No test required, but a little education will increase your enjoyment by a lot. A ham license will require a test and covers different frequencies.