nicely said people with big tris have big arms. Eating and protein really The arms are one of the hardest parts to grow being that they are a small muscle group it take a while to grow. How much bigger are we talking about here??
if youre an absolute beginner then practically anything will work, so long as you eat
if youve been in the game for a while, well youre looking at some pretty intense hormonal supplementation or a very very long time and a lot of frequent meals
There is no one way, but it's all about the heavy compound movements as said previously.
Also, in my personal experience it has been heavy BACK exercises that made my bicepts grow the most. Back exercises recruit the bicepts a lot, so focus on going heavy for back (ie heavy underhand bb rows, deads, chins).