How to add contacts from my iPhone to my new iPad

See this link --> Set up and use iCloud Contacts - Apple Support

If you are using the same Apple ID & password on both devices and you also have in

Settings > [your name] > iCloud > Contacts: ON

then if iPad is connected to the Internet via Wi-Fi, it will automatically sync over from iPhone.

if you restore the backup of the iphone to the ipad it should transfer

if you set it to synch contacts to icloud using the same appleID should make it transfer to