Want to backup at OneDrive

iOS/iPadOS does not natively support direct backup to OneDrive. This support page details the support the available methods to backup your iPad to iCloud - or a PC/Mac using iTunes/Finder:

How to back up your iPhone, iPad and iPod touch – Apple Support

There are third-party Apps available that can backup some data to other Cloud services - although these backups will not be a complete backup of the iPad.

only if you back it up to a computer which has mounted the onedrive sync dir as target for backup files