Thanks to @jr0cket’s spacemacs notebook. The https://practical.li/spacemacs/source-control/forge-configuration/ page has helped me multiple times for setting up verified commits in my spacemacs set up.
Thank you. There is also a section on setting up SSH keys for automatic git commit and tag signing (and local signing validation) in Practicalli Engineering Playbook. I find SSH keys easier than GPG keys. https://practical.li/engineering-playbook/source-control/git-configuration/#commit-signing-with-ssh-key