KDE Gear https://en.wikipedia.org/wiki/KDE_Gear https://apps.kde.org/

sudo apt-get install elisa
sudo apt-get install kate
sudo apt-get install ktorrent
sudo apt install partitionmanager
sudo apt-get install kmail
sudo apt-get install kdevelop
sudo apt-get install haruna
flatpak install flathub org.kde.haruna
sudo apt-get install koko
sudo apt-get install krita
flatpak install flathub org.kde.krita
sudo apt-get install Konqueror
sudo apt-get install Falkon 
NeoChat
https://apps.kde.org/en-gb/neochat/
sudo apt-get install Neochat
sudo apt-get install Kjournald
Kleopatra
https://apps.kde.org/kleopatra/
KOrganizer
https://apps.kde.org/en-gb/korganizer/
Krfb
https://apps.kde.org/krfb/