Mise-en-scène
The movie being in black and white gives it a sense of importance and seriousness. I feel like this adds to the effect of making the film seem older and more realistic in the fact that it makes you feel like it is being filmed back in the time during the war of 1939 in Poland, which leads to the feeling of authenticity and accuracy in the film.
The black and white also adds to the importance of the little girl wearing the red dress. Since she is the only color in the film it helps the audience remember how significant her presence is.
The different angles like in the photo below shows how the little boy is feeling belittled and afraid of Amon
Goeth.
Also, the SS Uniform and the little boys dirty clothes helps the audience understand that Goeth is someone of importance and the little boy is not.