My Ipad Pro does not update the IOS, it still remains 12.1 instead of Automatic update is on.

These support pages outline both the available methods by which the update can be performed - and troubleshooting should you experience difficulties:

Update your iPhone, iPad or iPod touch – Apple Support

If you can't update or restore your iPhone, iPad or iPod touch – Apple Support

If your iPhone, iPad or iPod touch won’t update - Apple Support

iOS update and restore errors – Apple Support

Be aware that your iPad may be too far behind the current version to be updated directly from iPad settings. As such, you will likely need to use a computer to perform the update. You will need access to either a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of MacOS). Ensure that your installed version of iTunes has been updated to the most recent version; the essential device drivers are included.

Download and use iTunes for Windows – Apple Support

Update to the latest version of iTunes – Apple Support

Update software on iPhone, iPad or iPod touch in iTunes on PC - Apple Support

If you're sure that your iPad model is an iPad Pro, it should support current iPadOS 14.4.2.

You can better identify your model using these instructions:--> Identify your iPad model - Apple Support

But, if it is still running iOS 12.1, something could go wrong while trying to update it wirelessly. Follow all the steps provided in this support article:--> If your iPhone, iPad or iPod touch won’t update

If the issue persists, you should try to update it using a computer running iTunes (PC) or iTunes/Finder (Mac). If you don't have a computer, borrow one from your friends, or ask for help at an Apple Store or Authorized Service Provider among this list:--> Apple – Location Selector

Regards

Giulio