Can Canary encrypt an email that is being sent to a person who does not use Canary?

Canary can encrypt an email that is being sent to a person who does not use Canary, as long as they have PGP setup via any other app, tool or service. In order to do so, please use Manual Encryption Mode. You can enable this mode via Canary > Settings > Security > Encryption Mode > Manual. 

Check this link to know more about Canary's Manual Encryption Mode.