Have you already set up your new iPad? If you haven't, you can set it up from the backup of your iPhone. See this link --> Set up your iPhone, iPad, or iPod touch - Apple Support
If you've already set it up and you want to sync things like contacts, messages, photos, music, etc., you should be using the same Apple ID you use on your iPhone on the iPad. Then go to Settings > Your Name, iCloud, Apple ID & iTunes > iCloud and make sure the services are turned on both devices and content will sync.
To use text message sync, use Continuity Services, which this link explains --> Use Continuity to connect your Mac, iPhone, iPad, iPod touch, and Apple Watch - Apple Support