How to check if the current page is at a specified path in the URL?

Question

I have a page marked as the Posts page that lists most recent blog posts.

It is at path /blog.

I want to know when the user is on this page so that I can display a list of categories of blog posts at the beginning of the page. I already did this in singular.php and in the rest of the cases in index.php.

For me is_home() returns true when on the landing page. And I use its behavior in index.php.

I tried a little to use this but it does not work:

get_page_by_path('/blog') == get_post()

So my current code is:

if (!is_home() || get_page_by_path('/blog') == get_post()) {
    get_template_part('template-parts/blog-categories');
}

and in the /blog page the blog categories are not shown. I am sure it is because of this condition in the if above.

Update 1

This condition does not work:

$_SERVER['PHP_SELF'] === '/blog'

because it is not /blog, but index.php (behavior build through .htaccess I guess).

Update 2

Translated: Blog - Articles Page

This is not considered front page.

Update 3

From this screenshot I think that home is Start (LP) and Blog is Posts page. Because of this I do not get why the is_front_page call is there:

if (!is_front_page() && is_home() || is_archive()) {
    get_template_part('template-parts/blog-categories');
}

Answer 1

You could try this instead

if (!is_front_page() && is_home()) {
    get_template_part('template-parts/blog-categories');
}

Explanation for the difference between front_page an home is here: https://wordpress.stackexchange.com/a/239838 if you set a page as a blog-page it is "home", in your case the landing-page is the so called "front_page". This is WordPress specific.