get .php of page template

hello,

i have created a page template and now the page is https://www.mysite.com/pagetemplate/

i want to get the pagetemplate.php file and i notice when i try for example to maybe do https://www.mysite.com/pagetemplate/index.php i get “redirected” and it is still https://www.mysite.com/pagetemplate/

i need to get this with the extention(.php)

is there a way to do so?