If you have a form with multiple checkboxes (categories, tags, ...) and you want to be sure, that at lease on checkbox is checked, you can add this validation:
public function store(Request $request)
{
$validatedData = $request->validate([
'category' => 'required',
]);
// more code
}
The ‘required’ validation checks, that there is at least one checked checkbox – all you need.