Turn on iCloud Photos on both devices
Sign in to both devices with the same Apple ID
On iPhone, go to Settings
Tap your name
Tap iCloud
Tap Photos
Turn on Sync this iPhone
On iPad, go to Settings
Tap your name
Tap iCloud
Tap Photos
Turn on Sync this iPad
Connect both devices to Wi-Fi
Open the Photos app on the iPad
Wait for the photos to sync
Use AirDrop
Turn on Wi-Fi and Bluetooth on both devices
Open Photos on the iPhone
Select the pictures
Tap Share
Tap AirDrop
Tap the iPad
Accept the transfer on the iPad
Use Messages
Open a conversation with yourself or another account on the iPhone
Send the pictures
Open the conversation on the iPad
Save the pictures to Photos
Use Files and iCloud Drive
Save the pictures to Files on the iPhone
Open Files on the iPad
Download or move the pictures to Photos
Use a computer
Import the pictures from the iPhone to the computer
Sync or transfer them to the iPad with Finder, iTunes, or iCloud Photos