Hi @Dandy Akhmad Rahadiansyah ,
Per my test, you can list all the files in the subfolder like this:
https://graph.microsoft.com/v1.0/sites/{site-id}/drive/root:/Folder/subfolder:/children
And you can use get files in subfolders like this:
https://graph.microsoft.com/v1.0/sites/{site-id}/drive/root:/Folder/subfolder/{item-path}
Hope this can help you.
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