How to add numbers pagination to this blog page?

First of all you need to get the paged query variable and pass it to your main query args:

//Protect against arbitrary paged values
$paged = ( get_query_var( 'paged' ) ) ? absint( get_query_var( 'paged' ) ) : 1;

$args = array(
    'post_type' => 'post'
    'paged' => $paged,
);

Then you have to add the following code at the place where you want the pagination to appear:

<?php
    $big = 999999999; // need an unlikely integer
     
    echo paginate_links( array(
        'base'      => str_replace( $big, '%#%', esc_url( get_pagenum_link( $big ) ) ),
        'format'    => '?paged=%#%',
        'current'   => max( 1, get_query_var('paged') ),
        'total'     => $post_query->max_num_pages
    ) );
?>