Practices for Teams admin

You can craete for free a Microsoft 365 Developer subscription: https://feedbackportal.microsoft.com/feedback/forum/ad198462-1c1c-ec11-b6e7-0022481f8472 If you work for a Microsoft Partner, you can also create a test tenant for different scenarios/use cases

Can you clarify what you are looking for? If you need guidance, best practices, etc, I suggest you take a look at the wealth of resources available over at docs.microsoft.com and the Learn platform. Here's a good start: https://docs.microsoft.com/en-us/microsoftteams/plan-teams-governance

If you want to "practice" your admin skills in a safe environment, just sign up for a free trial or Demo tenant, then play with it.