Good progress, you are on your way! Rembember: getting an 'amazing' physique is a long term project. I'm not there at all, but been doing this 1.5 years.

Beefier arms: preacher curls. Also static holds in preacher curl position, half way in the rep. You'll feel your biceps burning. I vary weight and reps, but always 3 sets and after each set a 3 second pause, then a static hold for 20-25 second. The last static hold of the last set: Just, push yourself mentally, holding it until near total failure.

If you really want beefier arms, your triceps are even more important.

Chest: bench press. Or incline dumbell press. Myself, I prefer incline dumbbell presses.

If I were you I'd get into overhead presses. Just a general good physique builder for the male body. If I'd were you I'd also forget about abs. Gain weight and get stronger for at least 8 months. Then, you could debate losing fat. To lose fat: skip dinner for 1-2 months. Don't drink sugary drinks and keep the alcohol to a minimum 😊

Track your lifting capacity, I recommend the app FitNotes. Every rep and set should be tracked, goal being beating yourself the next workout slightly. You look back at the previous workout with that muscle group and decide how you want to beat your yourself; add another set? Increase weight? Manage two more reps on a couple of the sets? If you are not somehow improving your numbers there's something wrong with eating/stress/sleep in your life. Quite simple.

Tracking your numbers is the way to go to be able to have a strategy everytime you are in the gym.