First, if you are giving-away or otherwise disposing of your iPad, you’ll need to prepare it properly:
What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support
As for synchronising your iPad and iPhone, you have likely been using iCloud to sync’ specific data and documents:
iCloud User Guide - Apple Support
You can select which items of data and documents are synchronised from device settings:
Settings > [Your Name / AppleID] > iCloud - enable the Apps and services that you wish to synchronise (on both devices)