// UserController.php
public function signin(Request $request) {

    $credentials = $request->only('email', 'password');
    $email = $request->input('email');

    // Check if login attempts above 3
    // Here I need to get the 'login_attempts' value
    $loginAttempts = AppUser::where('email', $email)->value('login_attempts');
    if($loginAttempts >= 3){
       // Response: To many attempts
    }

    try{
        // Some JWT  Auth validation
        }
    } catch (JWTException $e) {
        // Increase failed login counter
        // $attemptedUser->   <--- Here i need to increase the 'login_attempts' for the user with the email of the login request
        $attemptedUser->save();
    }
    // Some more validation and response
}

//Here you get the 'login_attempts' value

$loginAttempts = AppUser::where('email', $email)->select('login_attempts')->first();

$loginAttempts->login_attempts += 1;
$loginAttempts->save();