Override the Advanced Setting to hide excerpts if this is an Addon Package single post.

option_pmpro_showexcerpts_on_addon_packages.php

<?php
/*
 * Override the Advanced Setting to hide excerpts if this is an Addon Package single post.
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 *
 */
function option_pmpro_showexcerpts_on_addon_packages( $showexcerpts ) {
	if ( ! function_exists( 'pmproap_isPostLocked' ) ) {
		return $showexcerpts;
	}

	global $post;
	if ( ! empty( $post ) && pmproap_isPostLocked( $post->ID ) ) {	
		$showexcerpts = true;		
	}
	return $showexcerpts;
}
add_filter( 'option_pmpro_showexcerpts', 'option_pmpro_showexcerpts_on_addon_packages' );