This is currently not possible. If enabled, it would help a lot of users who rely on OneNote.
See this community discussion dating back 5 years with no resolution.
Agreed - whatever metadata is in OneNote which must be copied (hidden) into the Clipboard needs to be identified by SS and converted to plain text. I can copy text from OneNote and paste directly into Notepad—which is a very basic text editor—and it is recognized easily. So we need SS to put a little engineering prowess into decoding the clipboard content after OneNote is copied so that a paste operation inside SS pastes simply the text.
FYI, there's an idea from 2022 for this as well. As an extensive OneNote user, this is supremely annoying.
PLEASE ALSO VOTE HERE: Smartsheet + OneNote