Before you hire a photographer make sure they understand what you want for the delivery files. First specify that you expect true color reproduction as well as large JPG files. You would also expect the original file in the RAW format.
This would make it easier with the proper tools to fine tune each image file as needed in the future. If they don’t understand the term RAW file or say they don’t shoot RAW you will be paying for files that you have little control over. I suggest you move on to a photographer fitting the requirements outlined above.