There is no Page attributes because it’s not a page and by default WordPress doesn’t have an attribute to select template for post.
The page templates are coded in the theme that you are using.It seems that the theme has a template called Full Width defined as page template so you are able to select it for pages.
To not display the sidebar in the single blog post view you need to find out how it is being rendered either via single.php or index.php or by any other means.
If single.php is available in the theme and you find something like dynamic_sidebar('somename') then that’s responsible for displaying the sidebar. If get_sidebar() is available in single.php then look in the sidebar.php.To remove the sidebar you need to remove the corresponding sidebar and html structure also to make it full width.
The above explanation is for general cases and it differs depending on the theme.
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