How to make 2 similar functions more efficient

Question

You’ve passed those $upgrader_object and $options parameters to prefix_plugin_upgrade function. But you’re not actually using those parameters inside the function. So you can merge those functions like below-

/**
 * Update plugin settings on activate
 * Update plugin settings on upgrade
 */
function prefix_plugin_activate() {

    $new_option         = array( 'new_setting' => 'on' );
    $existing_settings  = get_option( 'existing_settings' );
    $new_settings       = array_merge( $new_option, $existing_settings );

    update_option( 'existing_settings', $new_settings );

}
// register_activation_hook( __FILE__, 'prefix_plugin_activate' );
register_activation_hook( PREFIX_PLUGIN_PATH . 'main-plugin-file.php', 'prefix_plugin_activate' );
add_action( 'upgrader_process_complete', 'prefix_plugin_activate', 10, 2);

Hope this is gonna help.