Writing this here in case it helps others: I couldn’t find any documentation in the manual for the file+head+olp or even file+head target type. It turns out that the description for these is in the org-roam-capture-templates variable docstring.
@nobiot Is it possible to take the heading under which I want to add the subheading as an input from the user rather than hardcoding it to a particular value?
@troam@nobiot Thank you so much for being helpful. This works for me. Although, I realized that I have to type in the exact heading or else it creates a new one instead of failing). Is there a way to rather let me choose from the existing headlines in the file? Or fail instead of creating a new one, thereby making sure no unnecessary headlines are created.
I think that you’d need to code your own thing if you really need a solution exactly as you describe.
If you have a few headlines for this capture and know what they are beforehand, you can list them in the capture template and select one when you capture a new note.