iPad ID

Presumably you refer to signing-out of your AppleID account from iPad settings. As for the ultimate impact, this will largely depend upon whether or not you have another device signed-in to iCloud with your AppleID.

When you sign-out, you will be presented with a warning about saving a copy of your iCloud data. If you choose to keep a local copy, this data will be downloaded to your iPad. If you don’t choose to keep a local copy, all iCloud data will be deleted from your iPad during the sign-out process. However, you’ll need to consider what happens to the data in iCloud:

1) If you have any other devices (such as a Mac computer or an iPhone) that are signed-in to iCloud, your iCloud data is safely retained in iCloud storage.

2) If you don’t have any other devices (such as a Mac computer or iPhone) that remain signed-in to Cloud, all data stored in iCloud will be deleted. You have a limited period of time before all data will be permanently deleted - after which recovery will no longer be possible.