Folders Within Folders Notes App

I am trying to use the notes app for schoolwork. I am organizing my work by creating folders within folders if the material is related. If I need to add a file to a note from another app, I can get access into the first folder, but if there are any folders within that first folder, they don't show up. For example, I click on my university's notes folder, and then inside of that folder there should be another folder named "Spring2023", and within that one, there would be my class folders with folders within them. However, when I enter my university's folder (the beginning of the folder tree) when trying to add a file to a folder's folder's note from another app, no additional folders pop up. I may have luck if I search in the search bar for the specific folder to add to, but that makes it harder. Is there a setting that is turned off for this, or is there no functionality for this implemented into the software yet?

Update: so I think this above description might be confusing, but it looks like in the notes app, all folders are on the left sidebar, and when you click a folder, another sidebar opens to the right of it that shows what is within the folder. I was wanting to know if there was a way that when you click on a folder from the sidebar, the contained folders are shown in addition to the notes within that folder.