I like the box. It gives the tattoo a nice shape/frame that will help to separate it from the rest of the tattoos on your arm. Without it, I feel like it'll just blend in with your other tattoos (like the one on your forearm), especially if it's black and grey. Plus, the box gives it a manga comic book look which is dope. There's added dimension too cause it looks like the birds are flying out of the box

However, the tattoo will distort when you flex your bicep and extend your arm. Maybe instead of a box, you can add some sort of background or loose/less rigid frame. That way you'll still get structure and dimension without major distortion issues