You can show the value using below code in,
/app/code/Vendor/Module/etc/frontend/di.xml
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
<type name="Magento\Checkout\Block\Checkout\LayoutProcessor">
<plugin name="ProcessReferrerConfiguration" type="Vendor\Module\Plugin\Block\Checkout\LayoutProcessor"/>
</type>
</config>
app/code/Vendor/Module/Plugin/Block/Checkout/LayoutProcessor.php
<?php
namespace Vendor\Module\Plugin\Block\Checkout;
class LayoutProcessor
{
/**
* Checkout LayoutProcessor after process plugin.
*
* @param \Magento\Checkout\Block\Checkout\LayoutProcessor $processor
* @param array $jsLayout
* @return array
*/
public function afterProcess(\Magento\Checkout\Block\Checkout\LayoutProcessor $processor, $jsLayout)
{
$jsLayout['components']['checkout']['children']['steps']
['children']['shipping-step']['children']['shippingAddress']['children']['shipping-address-fieldset']['children']['telephone']['value'] = '+91';
return $jsLayout;
}
}