That is up to you. I am a Registered Landscape Architect in Massachusetts. I prefer to draw plans and not manage projects. There are several reasons that I do it that way.
First is that my personality and skill set is as a designer rather than a manager.
The second is that I realized that the nicer higher end residential custom builders that are very active in my area prefer to get the project management money themselves. They know that if they refer me they will get a good solid plan that they can take bids on and I’ll stay out of their way. They make more money, so guess who they recommend to their clients? I spend $0 on marketing and I am buried in work.
I started as a side business and went full time about ten years ago. My full time work was in a civil engineering office before that. They had no problem with me doing residential landscape designs on the side as long as I did not solicit their clients.