Outside of Educational establishments, iPad and iPhone are principally intended to be a single-user device - and are not intended to shared in the same manner as you may be accustomed when using a Windows PC or Mac computer - which has multiple user profiles/accounts.
Be aware that for iPad and iPhone, signing-out of iCloud does not clear all locally stored data - and unless you are very careful when signing-out, you stand a very real risk of having your personal and/or sensitive data (such as your Calendar, Contacts and Keychain (Passwords) being merged with the AppleID/iCloud data next used to sign-in.