Multiple Accounts Logging into iPad

Outside of Educational and Enterprise 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.

For managed environments, where multi-user usage is possible, the Deployment Guide provides appropriate guidance.

Shared iPad overview – Apple Support

For unmanaged environments, be aware that if you sign-out of iCloud and other Apple services - and sign-in with a different AppleID - you’ll not be able to change back for 90-days. So as to prevent account abuse, some critical Apple services will only allow one change of signed-in AppleID (on a device) in a 90-day period.

Be aware that for iPad and iPhone, signing-out of iCloud does not necessarily clear all locally stored data. 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.

To completely sanitise an iPad or iPhone of all data, it is necessary to fully reset the iPad - which for most is too great a burden for simple user-switching.

Settings > General > Transfer or Reset iPad > Erase All Content & Settings

Also see:

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

In conclusion, unless you fully understand and accept the implications, you would be well advised to reconsider any attempt to routinely attempt use with multiple AppleID accounts - or sharing your iPad with another user.

iPads and iPhones are single user devices. If you log out and then into a new account items that you sync with iCloud will merge. Apps for one account will not likely work for the second account, etc. You can switch accounts if you first What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support