No matter how your WordPress metaboxes are created, whether it’s custom PHP code or an ACF plugin, you can use the same function to output them to a template:
How add metabox to your WordPress posts. Without plugin
March 18, 2022
echo get_post_meta(get_the_ID(), 'custom_field_key', true);
get_the_ID() – function that returns the ID of the post
custom_field_key – key of yours meta box
true – output by string, false – output by array