Can i create custom content type without define .yml file in module?
If your content type is fairly straight forward (i.e. using only Drupal's fields), you can create the content type within the http://localhost/admin/structure/types/add link and once you have it built the way you want it you can export it via: http://localhost/admin/config/development/configuration/single/export.

It will even give you the name of yaml file to boot!

If that avenue is not sufficient then you can follow: This tutorial about building custom drupal content entities; it is lengthy in nature, which is why I will elide the details.

And if you're going to use that tutorial, then I would suggest using drupal console to generate the boilerplate code for you.  It makes things quite simple.  Drupal Console, among other things, manages the generation of content entity boilerplate code.  It is quite helpful.