There are a lot of users asking to be able to create a team from a Template.
From UserVoice it says that creating Teams from Template is on the backlog : https://microsoftteams.uservoice.com/forums/555103-public/suggestions/16941814-team-templates
Last week at the SharePoint Conference North America, at the Microsoft Teams booth I saw that we could Create Team from Template. (See image below)
It would then show the list of available teams to use as a Template.
Don’t hold your breath, It’s still in testing, but it looks good.
Maybe you will see this soon in a tenant near you!