iTunes for Windows creates a local backup on the hosting computer. An iTunes backup has no reliance upon iCloud.
iCloud backups are straightforward and reliable. Don't forget, your iCloud data and backups are encrypted.
This support page outlines the natively supported backup methods for iPad and iPhone:
How to back up your iPhone, iPad, and iPod touch - Apple Support
Native iOS/iPadOS backup and restore processes are dependent upon iCloud, or connection to either Windows PC (with iTunes for Windows installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of macOS).
Natively supported methods offer full system backup - consisting of data and device settings.
How to back up your iPhone, iPad, and iPod touch - Apple Support
It is possible to use a third-party App to backup data (but not device settings) to a variety of external storage options - including third-party Cloud services, external media devices, network storage and file shares (and is therefore platform agnostic). One App that comes readily to mind is FileBrowser Professional by Stratospherix:
https://apps.apple.com/gb/app/filebrowser-professional/id854618029
You would be well advised to review the extensive online Manual and help files to determine suitability for your needs.
https://www.stratospherix.com/products/filebrowserprofessional/filebrowser-professional-user-guide.php
There is a learning curve, but it works.