create default document type for new sites

If you want to set these properties each time the page type is created in the content tree there are a few ways to accomplish this:

1. Create a global handler and set those properties on insert.
2. Create a partial class to override those value on insert.

Thanks for your response.
What is I want to add a page to all Kentico sites which only has 2 requirements : 1- has the failover keyword check 2- always be http and not https Do i need to do this under global handler as well?

If you want it to happen automatically then yes, add a global handler. If you want to do it manually then add that page type to the content tree and set the values in the Properties of that page by going to Properties>Security

Hello, I guess another approach is to add this new Page Type into one website and then export it as a pag type package and then import it, when you create the new website.

Now if you want this page type to be in the tree and also something that needs to be used for every new website, another approach is to create this page type on a blank website and add the relevant security settings for the page in the tree. Then use this as a website template for all new websites and you will have the page type with it's setting in place each time.