Every team in Microsoft Teams has a SharePoint site associated with it.
When you create a team, it will automatically create a classical Sharepoint site associated with the team.
Site design will determine what the Sharepoint site associated with your team will look like. It allows you to have a more personalized Sharepoint site than a classic Sharepoint site.
Powell Teams offers the possibility to choose a customized site design for your team once an advanced consent has been done for the tenant.
To add a site design into a template, edit the template from the template list:
Then, in the "Reference team settings" tab of the template, at the bottom of the page, you are able to select any of your existing SharePoint site Design: