I would like to use the pages I can see on the website template :
Where do I find it ? how can I import this page while using another Jevelin theme ( not the blog one )
I hope you are well today and thank you for your question.
It is a custom page created using the wpbakery page builder and not part of any demo content.
You can refer to the below WPbakery page builder documentation and create it.
You can achieve it as described in the below reply.
and for another template ,such as the “home photography” how can I use without uploading this particular theme ?
You have to create a whole page https://jevelin.shufflehound.com/home/home-photography/ from scratch including the slider that is very complex so a better way is to import the demo content.