The Notenik Edit tab is designed to let you edit any number of fields that might be available for your Collection (depending on its prefs), and to provide a variety of useful UI widgets for editing those fields, with the widget type and configuration depending on each field’s type, as defined within its template file.
That being said, the editing options for the actual body of a Note are adequate, but not particularly robust. Also, depending on the number of other fields in use, the space provided for editing the body of a Note might not be particularly generous.
For these reasons, and more, Notenik makes it easy to edit your Notes in whatever external text or Markdown editor you might prefer. Simply select the Text Edit Note action beneath the Note menu (or use the keyboard shortcut CMD-T) and your Note file will be opened in an external text editor. In my case, that’s typically BBEdit.
(And here’s another useful related feature – Notenik allows you to select from a variety of different file extensions in the Collection Preferences, and macOS let you set different preferred editors for different file extensions, and some editors allow you to set different editing options depending on the file extension.)
Here’s one more important point, though: after completing your edits in your external editor, you must save your edits back to disk in your editor and then, within Notenik, use the Reload Note action, again beneath the Note menu, in order for Notenik to be updated with the external changes.
I use this feature all the time, especially when using Notenik for longer-form Notes.