I have setup a SharePoint online Extranet site which I would like to allow access to for some of our other Office 365 tenants to be able to access. I have already followed this documentation https://docs.microsoft.com/en-us/sharepoint/create-b2b-extranet but when our other tenants try to access the Extranet site they still need to request permission. I would like them to be able to access the site as long as they are logged on with their own Office 365 accounts and not have to request access. Is this possible?
You could use identity governance features to manage the life cycle of access, including access to resources like SharePoint, yes. Do you have licenses for identity governance?