Currently OneNote have a 5 layer deep possible hierarchy for a given Notebook:
section group.
section.
page.
subpage (with collapsible option).
sub-subpage (without collapsible option).
...
lindalu-MSFT
Microsoft
MicrosoftHi, we apologize for the confusion where to post your OneNote feedback. This community was intended to be a temporary location to submit product feature suggestions between Microsoft moving off of UserVoice and the release of Microsoft's official Feedback portal app. Now that the latter is released, we encourage you to resubmit this great suggestion on the official OneNote Feedback portal at OneNote ยท Community (microsoft.com).
Kind regards,
Linda
Microsoft 365 Developer Platform community steward