The patio doors are likely to be tougher than the windows.
Basically, what we do in the north to cut down on the transmission of cold through windows and doors at least helps some against noise also. Largely this includes having more layers of glass between the inside and the outside.
For windows you can purchase at hardware stores (or at least could get if you were in a more northern location) storm windows that attach to the outside of the house outside of the current windows. However, getting the right size takes some care. We did three windows a few years ago and needed to carefully measure and get custom storm windows made for us. The local Home Depot or Lowe’s can do this and the cost is not too bad as long as the window can just be flush mounted to the existing trim. I mounted the storm windows myself. You can get windows with a single solid glass sheet which cannot be moved, or for a bit more can get windows where the glass is in two pieces, and the lower one can slide up and be replaced by a screen.
Unfortunately this doesn’t work for sliding glass doors. For those, we did in one case need to get them replaced. This is a relatively big deal even with a wood sided building where trim can be easily cut to size. If you get sliding doors that are meant for cold climate they will have at least two panes of glass, sometimes three for high end doors, which will be better than one pane.
I don’t think that any of this will be perfect. It will help some.
Another thing that might help some is to put a tall solid fence right on the property border. I am pretty sure that you need to put it on your side of the property line, and be careful that you actually do know where the property line is. I suppose that you could try to get the school to put one in on their side of the boundary.
By the way, insulating walls also reduces the transmission of sound through the walls. This is however hard to do on existing walls (much easier to do when initially building).
I doubt that building codes in California are quite up to New England or Minnesota standards with regarding to windows, doors, and insulation. I will admit however that I have not looked closely at California buildings for quite a while. I think that I had single pane windows when I lived out there, which you definitely don’t want if noise is an issue.
Also in the cold parts of the USA (and of course in our colder neighbor to the north) you can get blinds that roll down over the windows and doors. If you get ones that are meant to protect against cold in the north, they will also cut down on noise. These can be lowered or raised relatively easily (or at least the ones we have can be). Some have a honeycomb cross section which again implies two layers, which will help more against cold (where we live) or noise (where you live) compared to a single layer.
