Multiple logins for iPad

Sorry, no.

Other than managed devices in Educational environments, iPad is essentially designed to be a single user device. iPad does not support use with multiple AppleID credentials.

Not possible. Separate logins is not a function of iOS.

You could each use a different app for email and for

messaging, but unless the developers of those apps

provided a way to password protect the individual app,

anyone accessing the iPad could open and read any app.

You could put the iPad into kiosk mode to limit your child

to a single app, but that does not seem to be what you want

to do.