iOS 12.4 is likely the first software release that will support Apple Card, the new Apple Pay credit card with special features inside the Wallet app on the iPhone. Apple Card was first announced on March 25th ahead of a summer launch in the United States. Here you can upgrade to the first beta of iOS 12.4.

Step 1 Connect your iDevice to PC with genuine USB cable and launch 3uTools. 

Step 2 Go to Flash & JB →Easy Flash, select firmware iOS 12.4beta. If you want to upgrade with data, please check the box "Retain User's Data While Flashing". There will be a pop reminder after you click "Flash", please read it with caution.

You are recommended to backup your iDevice regularly in case of data loss.

Step 3 Confirm the stabilization of network and USB connection while flashing, wait patiently for around 5 to 10 minutes. Your iDevice will be restored to iOS 12.4 beta 1 after reboot.