Open Settings on your iPhone
Tap your Apple ID name at the top
Tap Find My
Tap Find My iPhone
Turn off Find My iPhone if needed
Open Settings on your iPad
Sign in with the same Apple ID on the iPad
Tap Privacy & Security
Tap Location Services
Turn on Location Services
Tap Find My
Turn on Share My Location
Tap Use This iPad as My Location
On your iPhone, open Settings
Tap your Apple ID name
Tap Find My
Tap My Location
Select your iPad
Confirm the iPad is set as the location device