Advice on aging retaining wall and concrete yard

New homeowner, looking for help on both what kind of professional I need, and recs for that professional.

My yard is 80% concrete, held up by a retaining wall on one side (the long side, the entire length of my lot from street to back of my yard), and runs right up to my neighbor’s brownstone wall on the other side. There’s a small garden on one edge of my yard (retaining wall side), but I have no idea how deep it goes or what’s under the top layer of soil & plants. There is a drain in the concrete that is connected to the main sewer line that runs through my house, and the slope of the concrete yard currently does a decent job of getting water down to the drain.

I’d like to have someone look at (1) the retaining wall which is beginning to lean out and advise me about repairs, and (2) my cracked concrete yard and tell me whether I can permanently remove any of the concrete without damaging my own lot/foundation or those of any of my neighbors, or if I have to replace the cracked concrete with new concrete. My ultimate goal is to create a nice yard space, prefera bly with less concrete and more garden/pavers/gravel, but not if it comes at the expense of the stability or drainage around anyone’s house. My best guess is that I need a landscape architect, but I’m not certain and I’m having a hard time even figuring out which landscape shops are actually architect-led. Or maybe I need some kind of engineer? All advice appreciated!