on the file:///F:/bedrock-server-1.6.1.0/bedrock_server_how_to.html it says in the permission part about adjust player specific permissions by assigning them roles in the permissions.json that is placed in the same directory as the server executable.The file contains a simple JSON object with XUIDs and permissions. Valid permissions are: operator, member, visitor. Every player that connects with these accounts will be treated according to the set premission. If you change this file while the server is running, then run the command permissions reload to make sure that the server knows about your new change.