Registration on these portals is usually free and allows you to compete on equal terms with the rest of your colleagues. If you think that you have everything you need to dedicate yourself to this profession, but you do not have enough clients to live on it worthily, it is possible that it is because you do not get to get to know you. You may have a communication problem.
If this is the case I cannot imagine a better way to jump into the ring. Once in it, whether or not you get personal training will depend on your professional ability and only on it. Do a good job, be honest with yourself and your clients, overcome the expectations of those who decide to give you a vote of confidence and, if you get it again and again, they will not hesitate to talk about you and recommend you.
Personally I do not understand why a coach who is starting, wanting or need to make himself known, or wants to increase his client portfolio, would not want to be in one of these search engines. That yes, choose well with whom you associate because, because of what we call transference, the image and subjective emotional perception that this portal has potential customers will also associate with you.