Do you want to link from within obsidian or from outside obsidian?
The URL scheme use case is for the latter (and I dont know if direct linking to a specified heading is possible with that).
But if you just want to link to a specified heading from within obsidian, that is from one note to another note, you don’t need the URL scheme. Just start by typing [[, then the first letters of the note you want to link to. Obsidian will give you a couple of propositions that match your first letters. Navigate to the note you want to link to (using arrow-down key), then press # - obsidian will show you all the headings within this note. Just chose one and it will be directly linked!
The link will be “relative” - means: not containing the absolute path on your OS, but just [[notetitle#heading]], or [[obsidian-subfolder/notetitle#heading]]