"All" is a relative term, there are many attributes that are not exposed via the admin tools or not even synced to Azure AD from the corresponding workloads. But if you know what specific attribute you are looking for, you can easily find the corresponding cmdlet (if one exists). Here's also a reference for what's available via the Graph API (again, not everything is listed): https://learn.microsoft.com/en-us/graph/api/resources/user?view=graph-rest-1.0
To add custom attributes, follow the steps here: https://learn.microsoft.com/en-us/previous-versions/azure/ad/graph/howto/azure-ad-graph-api-directory-schema-extensions