show modal view custom size

[attributes inspector]
check "Content Size" -> Use Preferred Explicit Size

if withNavigationBar {
   let navController = UINavigationController()
   navController.viewControllers = [some view controller]
   navigationController.modalPresentationStyle = .formSheet
   self.present(navController, animated: true, completion: completion
} else {
   vc.modalPresentationStyle = .formSheet
   self.present(vc, animated: true, completion: completion)
}