<referenceContainer name="sidebar.main">
    <block class="Magento\Framework\View\Element\Html\Links" name="customer_account_navigation_secondary" after="customer_account_navigation" template="Magento_Customer::account/navigation.phtml">
        <block class="Magento\Framework\View\Element\Html\Link\Current" name="customer-account-navigation-account-link-secondary"> <!-- duplicate this as many times as you need, just make sure the name is unique -->
            <arguments>
                <argument name="label" xsi:type="string" translate="true">Some link here</argument>
                <argument name="path" xsi:type="string">module/controller/action</argument>
            </arguments>
        </block>
    </block>
</referenceContainer>