When using Apple’s Smart Folio Keyboard on my 2018 iPad Pro, if I press shift-return in a note, Agenda inserts a new paragraph just like pressing Return. Pressing option-return works to insert a new line instead of a new paragraph, but I’d expect shift-return to work too like it does on macOS.
Looks like control-return has the same issue too. In macOS that just inserts a new line, but on iOS it inserts a new paragraph.