How to download the files using URL from salesforce

Note: To download the file, require the Content Version record Ids

For Single File

Use the below URL to download the single file from the salesforce.
URL:  https://<YOUR_SFDC_BASE_URL>/sfc/servlet.shepherd/version/download/068XXXXXXXXXXXX

String idCntDoc = '068XXXXXXXXXXXX';
String strURL = URL.getSalesforceBaseUrl().toExternalForm() + '/sfc/servlet.shepherd/version/download/' + idCntDoc;
System.debug('URL ===> '+strURL);

For Multiple Files

URL: https://<YOUR_SFDC_BASE_URL>/sfc/servlet.shepherd/version/download/068XXXXXXXXXXXX/068XXXXXXXXXXXX

above URL downloads the files in ZIP folder

list<String> lstCntVersionIds = new list<String>{'068XXXXXXXXXXXX', '068XXXXXXXXXXXX'};

String strURL = URL.getSalesforceBaseUrl().toExternalForm() + '/sfc/servlet.shepherd/version/download/';

for(String iterator : lstCntVersionIds) {
    strURL += iterator + '/';
}

strURL = strURL.removeEnd('/');

System.debug('URL ===> '+strURL);

How to get Salesforce Base URL in Lightning Web Component(lwc)

To get Salesforce base URL use the window.location object can be used to get the current page address (URL).
The window.location.origin property returns the origin URL of the current page.

Also Read:
How to get URL parameters In Lightning Web Components(lwc)

Ex URL: https://lwcpractice1-dev-ed.lightning.force.com/lightning/r/Account/001B000000vZWOHIA4/view

HTML File

<template>
    <lightning-card title="Salesforce Base URL in Lighting Web Component">
        <div class="slds-text-heading_medium slds-text-align-center">
            SFDC Base URL : <p></p><lightning-formatted-url value={sfdcBaseURL} ></lightning-formatted-url></p>
        </div>
    </lightning-card>
</template>

JS File

import { LightningElement } from 'lwc';

export default class BaseURL extends LightningElement {
    sfdcBaseURL;

    renderedCallback() {
        this.sfdcBaseURL = window.location.origin;
    }
}

Output