Creating a modern site (referred to as a site collection in classic architecture) is quite simple from the SharePoint Admin Center. Use the following steps to complete the task:

1. Navigate to the SharePoint Admin Center (https://tenant-admin.sharepoint.com).
2. In the navigation pane, select Active sites. On the Active sites page, select + Create.
3. Select the type of modern site you'd like to create (either Team site or Communication site). If you select Other options, you'll create a site without an Office 365 group.
4. Fill out the details by entering values in the Site name, Group email address, and Group owner fields. Select a language in the Select a language drop-down menu. If necessary, expand Advanced settings to modify privacy settings and the time zone and to enter a description. Click Next when finished:

5. Specify additional owners or members and click Finish.

Once you've created a modern site, you can either register it as a hub or associate it with an existing hub, if desired.