GNOME Disks can perfectly handle LUKS volumes, change passphrazes etc. While i do know that theres zulucrypt it would be very convinient and on-par with GNOME to have that functionality in KDE Partitioner
Can you elaborate on what you mean by etc. At the moment KDE Partition Manager can create / resize / open / close LUKS volumes. KDE Partition Manager indeed does not have support for changing passphrase. I think GNOME disks create / open / close but not resize LUKS.