Agenda is too good – I can see it being a great way to marshall large or even huge volumes of project research. But it would help to be able to leave a note expanded within a project, but to toggle paragraphs to expand or collapse within that note; is this possible already (and I haven’t found it?) or could it be added please?
To my knowledge the only way to fold / unfold is by using the header feature. You could put a brief descriptive paragraph title, number etc., even an emoji. Almost forgot the reason I started this. I sometimes use a tag such as #edit. Tag is searchable.
You can collapse sections, but not individual paragraphs. If you have a section with a heading or “parent” of some sort, you can collapse it using the button that appears in the space on the left. In the formatting palette there is a button there, but you can also Option-click the button to collapse.