You can find the documentation for email templates here.
Email templates have global variables that are common to all templates, including the user variable that provides access to the email recipients identity attributes.
In addition to global variables, each email template has its own set of variables. You can see these variables in the “Attributes” section at the bottom of an email template: New Account Provisioned Email Template - SailPoint Identity Services.
In your case, you can use the {identity} variable to reference additional identity attributes in the email. For example, if you need to display the department of the identity in the email, you can use {identity.department}.