In SharePoint Online, modern team sites are created with an associated Office 365 group, by default. Someone recently asked me if there was a way to create a modern team site without the Office 365 group. The way to do it is via creating the site via the APIs or PowerShell, and choosing the STS#3 template. If you're going to use SharePoint PnP PowerShell, you'll need to leverage the New-PnPTenantSite command to create the site. (This commandlet is for legacy site types) If you want to create a modern team site with the O365 group, or communications sites (no O365 group), you'll need to use the New-PnPSite commandlet.