My right arm is bigger (not length wise, muscle wise) than my left. I'm assuming it's somewhat normal because I'm a righty, but idk. Is there anything I can do for this?
Yeah that's pretty normal, mine is slightly as well. Do you work out? You should try using dumbbells rather than curl bars and such if you do, because no matter what your right arm is going to do a little more work on a long bar if you're a righty. If you use the dumbbells it's going to be completely unilateral training. Also, I usually do one or two extra reps with my left because it's not quite as strong and needs a little extra work.
this. and this Seriously though, single dumbell exercises are the way to go as your weaker muscle will build quicker when using the same weight.