get_template_part for specific page

This is just a supplement to the other answer.

I am trying to load fd-blog.php if it is the ‘Blog’ page, otherwise
load the fd-default.php

To actually load the template file, you should remove the dash (-):

get_template_part( 'inc/fd', 'blog' );    // loads inc/fd-blog.php
get_template_part( 'inc/fd', 'default' ); // loads inc/fd-default.php

So just inc/fd, and here’s the relevant code in get_template_part:

// Example when you call get_template_part( 'inc/fd', 'blog' ), $name below is 'blog'.
if ( '' !== $name ) {
    $templates[] = "{$slug}-{$name}.php";
}