Snippet #010 Filter posts by (Acf) Meta values https://since1979.dev/snippet-010-filter-posts-by-acf-meta-values/

get-posts-by-single-meta-value.php

<?php
$args = array(
    'post_type' => 'post',
    'meta_query' => array(
        array(
            'key' => 'os',
            'value' => 'MacOS',
            'compare' => '='
        )
    )
);

$macos_posts = get_posts($args);

print_r($macos_posts);
?>