If I view it in the layer source there's no crop, but as soon as I drop it into a composition it crops. The aspect ration on both the video and the comp are 1920x1080 so I'm not sure why it's doing this. Help is appreciated.
You have a misunderstanding here. AE doesn't auto-fit footage. Your video is 4k resolution, which is double the comp size. However, AE will fit/ zoom the comp and source viewers when they are set to auto. so all you have to do is use Layer --> Transform --> Fit to Comp or manually scale it to 50%. Given, that you plan on doing effects, ideally you would do so by pre-composing the resized footage to its own comp so it can be reused over and over without having to worry about such minutia.