kdewallet autounock db by login
you can leave the kwallet db password blank (but that's not secure)
or you can make the password for the kwallet database the same as the user's password on the system, and tell pam that sddm should use it for kwalletd as well:
echo 'auth optional pam_kwallet5.so
session optional pam_kwallet5.so
' >> /etc/pam.d/sddm
