You will need to transfer your saved data in-game.
*Please note that the data cannot be transferred by using the "Online Storage" feature of PS Plus.
So, please follow the steps below to transfer your saved data.
1. Start the PS4 version of the game, and go to "SYSTEM" > "Cross-Save Management" > "Upload Saved Data to Cloud Storage" to upload the saved data you wish to transfer.
2. Start the PS5 version of the game, and go to "SYSTEM" > "Cross Save Management" > "Download Saved Data to Cloud Storage" to save the data to New Save Data.