
When editing an Advanced Taxonomies block, grab the Block ID from the editor sidebar and paste it instead of the placeholder in the snippet below. This requires knowledge of WP_Query.
add_filter(
	'blocksy:general:blocks:tax-query:args',
	function ($query_args, $attributes) {
		if (
			isset($attributes['uniqueId'])
			&&
			$attributes['uniqueId'] === 'PLACEHOLDER'
		) {
			// Modify $query_args here
		}
		return $query_args;
	},
	10,
	2
);