Attachment template to show all images attached – and permalink

Hello there,

1- I need some help with making attachment template that shows all the attached images in a post. I did search and found a lot of codes but none did work for me, most probably because i have no knowledge in coding so i need it simple full template not just part of code to be put inside a loop.

Don’t care about the styling.

Example:

gsmarena.com

for mobile specification
It shows only featured image in the post and all the images attached for the phone shows in different page which is the attachment template.

I know that gsmarena is not using wordpress but i have seen a lot of wordpress sites function the same, unfortunately i don’t remember one of them now.
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2-If possible how to make the permalink for the attachment page like:

post link == domin.com/postname-postid.html
attachment page == domin.com/postname-pictures-postid.html