This is one very minor part of my business, and one that I hate the most. Heat, view distance, and TV height are all factors you may struggle with. There is far more here than can realistically be done by someone who is untrained. For starters, you will need power and low voltage cabling run to this location (unless you are going entirely streaming, in which case you just need power).

Generally the electrician is first man on site for a job like this. Their penetrations will allow you to see if there is a backer box or framing for the fireplace. If there is not one, it will likely need to be constructed to do this properly.

After the electric is run and the TV is mounted, you will also likely require a mantle to be within manufacturers spec for TV hanging. Most fireplaces require a 6-9" mantle set within a certain distance of the opening. You will have to check your fireplaces user manual or contact the company of manufacture. This is a common question they deal with.