Hello,
There was thread about how to make resetting password for user. Jmix 1.2 but for Jmix 2.x steps same.
I can suggest you use Keycloak instead of basic Jmix Auth. Its a bit complicated to configure, but provides huge functionality for User Management and other. If your project would be production-ready, keycloak is the best way.
Best regards,
Dmitry