You have heard the question asked hundreds of times I am sure, but the answer is simple.... NO!
Hollywood has projected what your Close-Protection Professional should look like and it is not true by any means. Does that mean that a 6'6", 300 lb. Protective Specialist can't get the job done? Absolutely NOT. But there is room for everyone in all shapes and sizes in this business.
Now if you are 5' tall, Do not expect to work directly with the client as the AIC/PSO. In fact the client may have a certain expectation that you as the service provider will have to meet. Education, Training, and Reputation will go a long way, and sometimes the client themselves will need to be educated. Client's have a preconceived image in their head already and go with the "Bodyguard/Sunshade image" that Hollywood has portrayed. So maybe the client does want the over 6' tall close protection specialist directly with them, then so be it, as long as he/she is more than qualified to fill that role.
On a Protective Detail, there are plenty of other key positions that someone of any size/height can fill considering they portray a professional image. The behind the scenes work on a Protective Detail are much more complex than one might imagine. You wont be the one in the spotlight, but will certainly be recognized internally as the one who got thin
Advances are a key factor on any protective detail. A Proper Advance can make or break a movement. You as a practitioner will want to ensure everything is available for the client. This includes the VIP reception that may or may not be available, the back entrance as to not draw attention depending on the threat. The Site survey in which you have to identify a place for a stash car in the event the main entrance is blocked due to an foreseen act. You are the main POC for the DL/SL that facilitates everything on venue ultimately making it a success.
A Driver has no size or height restrictions. Driving seems simple enough, but is actually one of the most complex positions on a movement. Drivers need to familiar with the routes, complete map studies the night before, be familiar with the dynamics of their vehicle knowing the capabilities and deficiencies. They also have to ensure the maintenance is up to date, fueled up, and of course clean. Drivers IMO have the most extensive job of everyone. And in the end, they have to know how to DRIVE!
In the end, do not get bent out of shape if a position lists a certain size requirement. The Client will always want what they want and sometimes that is not negotiable. The Vendor has a complicated task satisfying the client as well as ensuring they have competent personnel on staff for the detail.