You make anything more "defined and tight" by lowering bodyfat. That's true wherever the fat is, biceps or anywhere.
So when you say "most people in the gym..." it is the same as saying "most people in the gym have high bodyfat." Sounds like you go to one of those old skool weighlifter/powerlifter gyms that smell of body odor, where it's not about what you look like, but how much you can lift
And no, apart from that scary chemical destruction of body fat they are experimenting with in Europe, there's no way to "target" specific areas of fat to remove. You can only control the entire system in total. The fat will disappear and reappear in patterns that are related to whether you're a male or female and to your specific body makeup.
Luckily, you're a guy, and bodyfat on guys tends to disappear first (and appear last) in the shoulders and upper arms. The last place it disappears, on guys (and the first place it appears), is the gut.
So if you drop body fat, it's possible your arms will be the first place you notice it. Note I said "possible" -- all this is dependent on your specific body makeup, which only you can know and is different than anyone else.