Reorder Content Types in ("/node/add")? In drupal 7 it can be do like this. 7 - Reorder Content Types in ("/node/add") - Drupal Answers

How can I reorder Content Types with Drupal 8?
Drupal 8 doesn't respect the menu structure anymore when displaying the node types. Node types have no weight concept, so there is no direct way to control this.

What you could do is to implement a template/preprocess for node_add_list/node-add-list.html.twig and then reorder the types in code.