You can't let your bird live in an empty cage. That's like having a house without any furniture and never being able to leave. You'd be really bored, right? Treat your bird properly and stock that cage with an entertaining diversity of perches, toys, and places for food. The cage can't be so full that your bird can't fly around and live happily, though.
Don't worry, these accessories come in all the varieties and usually cost under $5 or $10. Such a small investment for so much joy with your pet. This also means you can afford to replace them when they get when they get worn out.
Your bird will need somewhere to stand and several of these, of different lengths, from many angles, make for an exciting cage. This is where you get to decorate. Have a blast.
You've got to feed your bird something. And you've got to put that food and somewhere. Anything is fine here, as long as your bird will eat out of it.
These can also go in your cage for even more enjoyment for your bird.