try that ...

public function loginpost(Request $request)
{
       
  $field = filter_var($request->input('email'), FILTER_VALIDATE_EMAIL) ? 'email' : 'phone';

   if(Auth::attempt([$field=> $request->input('email'), 'password' => $request->input('password')], true))
     {
              return 'you are logged in';
      }
       else
       {
             return 'error';
        }
        
    }

Thanks! That takes care of part of my problem.

I currently have a more verbose solution in place at the moment. Granted its not very elegant, but it works for now, and fulfils my workflow / response requirements.

$email = Validator::make($request->all(), [
    'identity' => 'required|email|exists:users,email|min:5|max:100',
]);

$phone = Validator::make($request->all(), [
    'identity' => 'required|regex:@\+\d{1,3}\s{1}\d{3,4}\s{1}\d{6,8}@|exists:users,phone|min:5|max:100',
]);

$password = Validator::make($request->all(), [
    'password' => 'required|min:5|max:100',
]);

if ($email->passes() && $password->passes())
{
    // Attempt Auth using email and password
}
elseif ($phone->passes() && $password->passes())
{
    // Attempt Auth using phone and password
}
else
{
    // Validation failed
}