Solution is here
https://learn.microsoft.com/en-us/answers/questions/1517358/cannot-import-microsoft-graph-modules-import-modul
and here
https://github.com/microsoftgraph/msgraph-sdk-powershell/issues/1488

1. Ensure you have installed the module using Install-Module Microsoft.Graph -Scope YourPrefferedScope(CurrentUser/AllUsers) doc link here then verify if installed using Get-InstalledModule Microsoft.Graph

2. Please increase the $maximumfunctioncount to the max 32768 and try and load the Graph Modules that you need- Reference for existing modules . Including necessary modules will free up capacity.

3. You can run the Import-Module Microsoft.Graph to allow for the cmdlets to be available for the PowerShell session.