You shouldn’t modify any original theme code as when you come to update the theme in the future your code will be overwritten and need adding again, this will be required after every single update.
You should create and install a Child Theme which will allow you to create a modified version of the singular.php file, which this theme uses instead of using separate single.php and page.php files (Template Hierarchy).
You can simply make a duplicate copy of the file, put it in your child theme folder and modify it to suit.
Child theme files are safe from being overwritten when updating the main theme (Parent Theme).
Hope this helps.
