Limited Web Parts for Modern Sites

Hi, 

We're looking to publish a new Intranet for our business and so I have been playing around with SharePoint Online. I have to say i really like the modern style sites. However, I have followed a few videos online and see that they have a much wider range of web parts available to them when editing team sites (such as; Planner, Group Calendar and even some connectors like twitter). 

I was wondering is there anything i need to do, some sort of feature that needs to be enabled at the site collection level? - so that i can have more web parts available. 

Any advice is greatly appreciated, thanks.