(Optional) If required by your ROM, go back and flash the GApps zip file right after.

Modify status bars, themes, fonts, and system gestures. Top "Hot" Custom ROMs for Samsung Galaxy J4 Plus

Unlocking the bootloader will permanently break Samsung Pay and Secure Folder .

Flashing a custom ROM will trip Samsung Knox to 0x1. This means:

Have you tried any of these ROMs? Leave a comment on the XDA Developers forum thread for the J4 Plus. Flash safely!