Once created, you can let your window Manager/DE manage the passphrase

 pacman -S ksshaskpass

• ~/.config/autostart-scripts/ssh-add.sh

#!/bin/sh
ssh-add -q ~/.ssh/key1 ~/.ssh/key2 ~/.ssh/key3 < /dev/null

 chmod +x ~/.config/autostart-scripts/ssh-add.sh 

• .config/plasma-workspace/env/askpass.sh

#!/bin/sh
export SSH_ASKPASS='/usr/bin/ksshaskpass'

 chmod +x .config/plasma-workspace/env/askpass.sh 

 ssh-copy-id -i ~/.ssh/mykey user@host

• https://wiki.archlinux.org/index.php/KDE_Wallet#Using_the_KDE_Wallet_to_store_ssh_key_passphrases