Similar to Resident Evil 2 and 3 Remake .
To get the full experience, especially if you are using a base game dump, you will need the latest . 1. Resident Evil 4 Remake Updated Version resident evil 4 remake ps4 rom pkg update dlc link
Yes, installing an update pkg will not delete your save data, but it is always recommended to back up your saves to USB. Similar to Resident Evil 2 and 3 Remake