Not necessarily…
When signing-out from iCloud, you will offered the opportunity to keep a local copy of your data (e.g., Calendar, Contacts, Notes, Keychain Passwords etc.). If you wish to keep this data, accept the data that you wish to keep available. If this opportunity is declined, this data will be wiped from your iPad as you sign-out from iCloud.
After signing out, a restart of the iPad is recommended:
Restart your iPad - Apple Support
After restarting, you can sign-in to a different AppleID account from iPad settings. Any iCloud data that you saved to your iPad, during the previous sign-out, will be merged with your new AppleID account. You should note that once merged, there is no “undo” option. If reversal is required, the merged data must be manually deleted, entry by entry.