For your iPad and iPhone to “synchronise”, they must both be signed-in to iCloud with the same AppleID. Note, however, that email is not directly synchronised between your iPad and iPhone - but instead you must manually add your email account(s) to each device from which you intend to access your email:
Add an email account to your iPhone, iPad, or iPod touch - Apple Support
For other services to synchronise via iCloud, having ensured that devices are signed-in with the same AppleID, enable the services that you wish to synchronise:
Settings > [Your Name / AppleID] > iCloud - enable services and Apps as required
For more information about using iCloud, see: