I am thinking of making a button box where you can control media functions (pause, play, skip, etc) I have seen you can make a keyboard with key commands like ctrl alt etc. Is it possible to make a button box with the commands? if so what is the code for it?
Yes it is. The code is up to you to write. We are are not going to do your project for you.
I mean what is the code as in what do I have to write to call the function? (is it something like keyboard_play?)
See the Wiki and read about the different keyboard types: https://github.com/NicoHood/HID. Then look at this example: https://github.com/NicoHood/HID/blob/master/examples/Consumer/Consumer.ino. You will find all the possible media keys here: https://github.com/NicoHood/HID/blob/master/src/HID-APIs/ConsumerAPI.h.