There are 2 options how to include the date in e-mail templates:
1. Use $date variable - this variable will be replaced by date in the application default format based on application default language.
For example: Chat transcript from: {$date}
2. Use $timestamp variable and format it using Smarty date formatting.
For example: Chat transcript from: {$timestamp|date_format:"%Y/%m/%d"}
More info about Smarty date formatting here: https://www.smarty.net/docsv2/en/language.modifier.date.format.tpl