Use a cross-platform app like Google Photos, Dropbox, or OneDrive
Upload the pictures from Android
Open the same app on iPhone
Sign in with the same account
Download the pictures on iPhone
Use email or messaging apps to send the pictures
Attach the pictures on Android and send them to iPhone
Open the message on iPhone and save the pictures
Use Bluetooth only if both devices and apps support it
Use a file-sharing app like SHAREit or Send Anywhere
Install the same app on both devices
Send the pictures from Android
Accept the transfer on iPhone
Use a computer as a middle step
Copy the pictures from Android to the computer
Transfer the pictures from the computer to iPhone using iTunes or Finder
Use iCloud Drive if the pictures are uploaded from Android through a browser or app
Open iCloud Drive on iPhone and download the pictures