if you are here in New York which is in the USA yes therapists can change their focus / and type of clients they want to work with and what type of therapy they want to provide.

example a therapist who works here at the crisis center can at any time decide to open a private practice and be a yoga instructor, or a marriage counselor, or work just with children or work focusing only on DBT, or CBT, or EFT or even a life coach where they work with clients who have trouble dealing with day to day struggles in all areas of their life...

getting certified or licensed in the state of New York means you are qualified to be a therapist or psychiatrist or psychologist. it doesnt mean you can only work using one type of therapy, or not specialize in a set area of healing. it just means the state of New york recognizes you are now qualified to be a therapist, psychiatrist or psychologist in any area of the mental health field.career.

my own therapist works with all kinds of therapy but her specialty is deep relaxation such as hypnotherapy, yoga and other mindfulness therapies. At any point if she wishes she can turn her private practice into a yoga , mindfulness, hypnotherapy agency