List all your keys.
gpg -K gpg -K --keyid-format=long # Long version shows the key id
Create a new key.
Gpg has a global configuration directory where all the keys go by default which can make it hard to manage subkeys.
mkdir /tmp/gpg sudo mount -t ramfs -o size=2M ramfs /tmp/gpg sudo chown "$USER:$USER" /tmp/gpg gpg --homedir /tmp/gpg --import /path/to/other/keys gpg --homedir /tmp/gpg --list-secret-keys
It is best practice to keep a root signing key in an air-gaped environment and to use it to sign additional encryption keys called subkeys.