I don't really undestand your question, but you can do this
Job::where('disabled_hub', '=', '0')->with([
'positions' => function ($queryPositions) {
$queryPositions->where('queryPositions', '=', '10') );
},
'locations' => function ($queryLocations) {
queryLocations->where(''region', 'US');
}
])->get();
Or in your case a whereHas makes more sense
Job::where('disabled_hub', '=', '0')->with(['positions' => function ($queryPositions) {
$queryPositions->where('queryPositions', '=', '10') );
}])->whereHas('locations', function ($queryLocations) {
queryLocations->where(''region', 'US');
})->get();