Best advice for me I had a period where I was training biceps 4x per week usually after my main gym session end result was that my arms with a pump got up to 17 and half inches all natural

For me I love barbell curls cable Machine rope curls cable Machine one arm curls and dumbbell hammer grip curls. I used a ton of volume like I was doing for each exercise 10 sets of 15 reps light to medium weight really focus on contracting the bicep alot of guys end up curling big weight but the arms dont grow for me light to medium weight got the most growth.

I also had a period where I was focus on doing strict bodyweight chin ups for me that exercise was awesome for my biceps. Look at male gymnastics that do rings they have literally crazy biceps and they focus alot on pure weight training take note they do alot of straight arm bicep work.

My friend only dose bodyweight he's arms are pretty solid he's biceps stand out and he says that pure chin ups and even pull ups really helped for his arms he also said that one arm chin ups best exercise.

Another thing to remember if you want big arms don't just focus on biceps triceps make up more of the arm and when built they look way more better than biceps another friend literally for triceps dose skull crushers with heavy weight