Magento 2: How to defaultly open "content 2" tab?

Magento 2 docs - Accordion

Set active to the tab you'd like to be open by default instead of true. For example:

$("#element").accordion({ active: "0 1"});
$("#element").accordion({ active: [0,1]});

So in your case it should be:

data-mage-init='{"accordion":{"openedState": "active", "collapsible": true, "active": "2", "multipleCollapsible": true}}'

Replacing 2 with the tab you require to be open.

TLDR

Change "active": true, to "active": 1 where 1 is the tab you wish to be open by default.

On page Load Dynamically require to open some particulate tab please use below code instade of

data-mage-init='{"accordion":{"openedState": "active", "collapsible": true, "active": [1,4], "multipleCollapsible": true}}' 

Solution

require([
    'jquery',
    'accordion'
], function ($) {
    'use strict';

    jQuery( document ).ready(function() {                      
        jQuery( "#narrow-by-list" ).accordion({
            "openedState": "active",
            "collapsible": true,
            "active": [1,4], /** Integrat Dynamic open tab  */
            "multipleCollapsible": true,
        });
    });                 
});