8 – What is the correct way to cancel a template of a custom module?

I found a paragraph in the documentation on the use of template files in a custom module. This way, you can even use it to override a template like I did here.

However, I wonder if this is the correct way since I have read this response (what does not seem to work with the dynamically generated suggestion).

After some research I noticed that sometimes we can see the use of:

  • hook_theme_registry_alter
  • hook_theme single
  • hook_theme with hook_theme_suggestions_HOOK_alter

Apparently there is no clear documentation in this regard.

Is there any difference between adding a template and replacing a template from a custom module?
If so, what is the correct way to add a template and the correct way to cancel a template?