By default, the sending of emails is being handled by WordPress. Buddyboss Theme/Platform does not have a setting to change the displayed email sender in the email notifications.
Nevertheless, you may check this article https://www.wpbeginner.com/plugins/how-to-change-sender-name-in-outgoing-wordpress-email/ as a reference to achieve what you want.
Note: If the plugin is not listed on our integrations page: https://www.buddyboss.com/integrations/, we cannot guarantee that a third-party plugin will work well with our BuddyBoss Theme as we haven't tried it extensively and also we don't have an integration nor a built-in function with such a feature yet. You are free to try, and we are happy to know how it works on your end.