mymodule.page_detail:
path: '/detail/{Title}/{ObjIdentifier}'
defaults:
_controller: 'DrupalmymoduleControllermyController::detailpage'
Title: ''
ObjIdentifier: ''
ViewPdf: '0'
...

mymodule.page_detail_pdf:
path: '/detail/pdf/{Title}/{ObjIdentifier}'
defaults:
_controller: 'DrupalmymoduleControllermyController::detailpage'
Title: ''
ObjIdentifier: ''
ViewPdf: '1'

if (isset($myModuleViewPdf) && $myModuleViewPdf == "1") {
  ...

$print_engine = Drupal::service('plugin.manager.entity_print.print_engine')->createSelectedInstance('pdf');
$print_builder = Drupal::service('entity_print.print_builder');