If your base has a spouses page of any sort you could definitely ask them! That’s how I found my OB! Or a lot of the medical facilities in my area have a “get to know the doctor” section on their website.
They always assign you to a 'team' so if you don't like your particular PCM ask for another team member when making the appointment and through the process of elimination, find one you like. Then go online to the Tricare website and switch to that doc or just ask for that team member each time by name.
Unfortunately you have to. They have to assign you a pcm