How to load ACF JSON files from additional directories. See https://www.awesomeacf.com/snippets/load-acf-json-files-from-multiple-locations/ for more details.

register-acf-json-load-directory.php

<?php

add_filter( 'acf/settings/load_json', function ( $paths ) {

	$paths[] = get_template_directory() . '/some/custom/dir';
		
	return $paths;

} );

register-multiple-acf-json-load-directories.php

<?php

add_filter( 'acf/settings/load_json', function ( $paths ) {

	$paths[] = get_template_directory() . '/some/custom/dir';
	$paths[] = WP_CONTENT_DIR . '/uploads/some/custom/dir';
	$paths[] = '/some/system/path/dir';

	return $paths;

} );