The game sold 610,077 units on its first week in Japan
https://twinfinite.net/2019/01/kingdom-hearts-3-resident-evil-2-media-create/
For comparison,
this are the first week sales of other notable PS4 games:
#1 Monster Hunter World - 1,350,412
#2 Dragon Quest XI: Echoes of an Elusive Age - 950,338
#3 Final Fantasy XV - 716,649
#4 Knack - 322,083
#5 Metal Gear Solid 5: The Phantom Pain - 315,288
#6 Persona 5 - 268,320
#7 Dragon Quest Heroes: The World Tree's Woe and the Blight Below - 255,292
#8 Resident Evil 2 (Remake) - 252,848
#9 Call of Duty: Black Ops 4 - 233,762
#10 Resident Evil 7: biohazard - 231,188
This would make KH3 the forth best FW seller on PS4.